Dear Geostatisticians,
Am using Geo-EAS to analyse some data sets. My interest among others
is to view the kriging weights, variance. And/Or can I be pointed
to a kriging software that can help with these parameters.
Thanks,
Lawrence
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Dear list members,

I would like to put forward a job announcement (2-year Post-Doctoral
position) that has arisen within my Unit for a person with knowledge of GIS
and geostatistics for your consideration. Please distribute it as you see
fit. Thank you very much for all your help.

Carlos

****************************************************************************
***************************************************************
The candidate main line of work will be the assessment of environmental
parameters derived from satellite and other sources and their possible
influence in the field of fisheries. The work will include the Time Series
Analysis of the environmental parameters as well as the application of
multivariate statistics for the determination of possible relationships
between spatial patterns of environmental data and fish distribution and
recruitment . Participate in research on Geographic Information Systems
(GIS) involved in the management of marine resources.

Requirements:

Scientific: A Ph.D, or equivalent. Good knowledge of statistics and
Geographic Information Systems. Knowledge of the techniques used in the
operation of computer-oriented scientific information services, like image
processing, matrix manipulation etc... Knowledge of fisheries and/or remote
sensing an advantage.

Personal: The candidate must be a European National. Initiative, high sense
of responsibility and ability to plan and organize work is a must as is the
ability to write clear, concise summaries of complex scientific/technical
material.

Any person interested, please forward curriculum vitae, to the attention of
Carlos Villacastin at the address below:

Carlos A. Villacastin Herrero
Marine Environment Unit
Space Applications Institute
Joint Research Centre
TP 272
Ispra (Va)
21020
Italy

Phone: +39-0332-789924
Fax:   +39-0332-789034
E-mail: carlos.villacastin@...
****************************************************************************
********************************************************************

Carlos A. Villacastin Herrero
Marine Environment Unit
Space Applications Institute
Joint Research Centre
TP 272
Ispra (Va)    Phone: +39-0332-789924
21020          Fax:   +39-0332-789034
Italy

E-mail: carlos.villacastin@...
         cvillacastin@...

Our sincere apologies for cross posting.  Please post or circulate
the following announcement.  Thank-you!

-------------------------------------------------------------
   STATISTICS AND HEALTH: Edmonton Statistics Conference
            June 11-13, 2000, Edmonton, Alberta
        Call for Advance registration by May 1, 2000
-------------------------------------------------------------

Organized by the Biostatistics Research Group, Statistics Centre,
Department of Mathematical Sciences at University of Alberta, Edmonton,
the conference aims to provide a catalyst toward understanding
the role of statistical sciences in scientific research, facilitating
communication among relevant disciplines.

The featured speaker is Bradley Efron (Stanford) on
"BOOTSTRAP BIOSTAT".  The invited speakers are as follows:

* CORRELATED DATA IN HEALTH RESEARCH: Rao, JNK (Carleton);
Heagerty, P (Washington); Wang, MC (Johns Hopkins)
* META-ANALYSIS AND ERRORS IN ESTIMATION: Berlin, J (Pennsylvania);
Greenland, S (UCLA); Moher, D (Ottawa)
* SPATIAL MAPPING OF DISEASE RISKS AND SMALL AREA ESTIMATION:
Dean, C. (Simon Fraser); Waller, L (Emory); Walter, S (McMaster)
* HIERARCHICAL MODELS-NEW DEVELOPMENTS: Lawson, A (Aberdeen);
McCulloch, C (Cornell); Normand, S-L (Harvard)
* COST, COST EFFECTIVENESS AND DECISION ANALYSIS: Bryant, H
(AB Cancer Board); Manning, W (Chicago); Philipson, T (Chicago)
* EPIDEMIOLOGY AND METHODS: Gentleman, J (Nat'l Center For Health
Stat); Liang, KY (Johns Hopkins); Morgan, K (McGill)/Bull, S (Toronto)

For more information, visit the conference website at
www.stat.ualberta.ca/~brg/conf.html or inquire at brg@....
To qualify for the early discount rates, registrations must be
postmarked, faxed or emailed before May 1, 2000.

===========================================================
K.C. Carriere
Associate Professor of Statistics
Department of Mathematical Sciences
University of Alberta 		 (tel)780-492-4230
Edmonton, AB T6G 2G1 	 (fax)780-492-6826

  Home: www.math.ualberta.ca/~kcarrier/kcarrier.html
  Visit:www.stat.ualberta.ca/~brg
===========================================================








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Dear subscribers of the geostat list:

I would like to ask what "modern" software you recommend if one would like
to perform "cross validation" on your interpolated data set. I am currently
using SURFER 7 so it would be an advantage if the recommended program could
use the out-put files from SURFER.

With best regards./J

Johan Holmqvist
Chemical Engineering II, Lund University
P.O. Box 124,
S-221 00 Lund
Sweden

johan.holmqvist@...
Tel:     +46 46 222 04 08
Fax: 	   +46 46 222 82 74

To all persons interested (in particular
North American Geostatisticians),

I want to let you know that the 2000 NACOG meeting
will take place in Southern Michigan on August 10th
through August 13th at the Kellog Ecological Station,
near Kalamazoo.
More information on the meeting can be found at:
http://www-personal.engin.umich.edu/~goovaert/nacog.html

Regards,

Pierre
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

   ________      ________
  |        \    /        |    Pierre Goovaerts
  |_        \  /        _|    Assistant professor
  __|________\/________|__    Dept of Civil & Environmental Engineering
|                        |   The University of Michigan
|     M I C H I G A N    |   EWRE Building, Room 117
|________________________|   Ann Arbor, Michigan, 48109-2125, U.S.A
   _|    |_\    /_|    |_
  |        |\  /|        |    E-mail:  goovaert@...
  |________| \/ |________|    Phone:   (734) 936-0141
                              Fax:     (734) 763-2275
                              http://www-personal.engin.umich.edu/~goovaert/

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>


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dear List,
here at the Faculty of Agriculture of the University of Padova we have
started a research project on precision farming (i.e. cultivation practices
able to take into account the intra-field spatial variability thanks to new
machineries, GPS, GIS, etc.).

We are now planning data acquisition activities to describe the spatial
variability of soil characteristics, weeds, pests, etc., within the
cultivation unit. Geostatistical analyses will be applied to the results of
field data collection.

At this regard we will appreciate very much to have suggestions from the
List about specific methods for spatial sampling oriented to operational
applications (references, web resources, etc.).

I will summarise the results.

Thank you in advance,

Carlo Giupponi
_________________________________________________________
Dipartimento di Agronomia Ambientale e Produzioni Vegetali
Universita' di Padova
Via Romea, 16 I-35020 Legnaro (PD) Italia
Tel ++39-049-8272837 Fax ++39-049-8272839
_________________________________________________________

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Physica-Verlag
    A Springer-Verlag Company

    CALL FOR CONTRIBUTIONS

    SOFT COMPUTING FOR RESERVOIR CHARACTERIZATION AND MODELING

    Reservoir characterization and modeling plays a vital role in modern
    reservoir management. It maximizes integration of multivariate data and
    reduces the uncertainty of reservoir predictions. It helps to make sound
    engineering decisions and improves the asset value of the oil and gas
    companies. Soft computing, a collection of various intelligent
    techniques including neural networks, fuzzy reasoning, evolutionary
    computing and hybrid models, is increasingly popular. Unlike the
    conventional hard computing, soft computing is tolerant of imprecision,
    uncertainty and partial truth, and hence producing overwhelming results
    over conventional methods in many published studies.

    In response to this, we would like to call for contributions for a
    special edited book on “Soft Computing for Reservoir Characterization
    and Modeling,” to be published in the popular series Studies in
    Fuzziness and Soft Computing by Physica-Verlag, a Springer-Verlag
    company. The contributions must be new and original. The topics include,
    but not limited to, the followings:

    Advanced and innovative techniques
    Geophysical data processing
    Numerical geology
    Well log analysis
    Reservoir mapping and 3D modeling
    Reservoir upscaling
    Reservoir engineering
    Multidisciplinary studies
    Field applications

    The deadlines are:

    Submission of abstract proposal (max 300 words): 1 May 2000
    Notification of acceptance: 15 June 2000
    Submission of full manuscripts: 1 August 2000
    Submission of camera-ready version: 15 January 2001
    Expected publication: June 2001

    You are encouraged to submit the abstract to Dr Patrick Wong via email
    at pm.wong@...

    Editors:

    Dr Patrick Wong
    School of Petroleum Engineering, University of New South Wales, Sydney,
    NSW 2052, Australia.
    Tel: +61-2-9385 5189; Fax: +61-2-9385 5936; Email: pm.wong@...

    Dr Fred Aminzadeh
    FACT Inc. and dGB-USA, 14019 SW Freeway, Suite 301-225, Sugar Land, TX
    77478, USA.
    Tel/Fax: +1-281-313 2028; Email: faz@...

    Dr Masoud Nikravesh
    Energy and Geoscience Institute, University of Utah, Salt Lake City, UT
    84108, USA.
    Tel: +1-801-585 7013; Fax: +1-801-585 3540; Email:
    MNikravesh@...

    Series Editor:

    Professor Janusz Kacprzyk, Systems Research Institute,
Polish Academy of
    Sciences, Warsaw 01-447, Poland.
    Volumes published:
    http://www.springer.de/cgi-bin/search_book.pl?series=2941

Gregoire Dubois
Section of Earth Sciences
Institute of Mineralogy and Petrography
University of Lausanne
Switzerland

Currently detached in Italy

http://curie.ei.jrc.it/ai-geostats.htm

____________________________________________________________________
Get free email and a permanent address at http://www.netaddress.com/?N=1
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Hello !
I am a beginner in geostatistics and have some questions concerning trend
and zonal anisotropy.
In my data of cloud cover in germany I have an obvious trend of decreasing
cloud amount from north to the south. I have a zonal anisotropy too, with
the following variogramms:
North-South
linear with sill, Nugget 0.005 Sill 0.06 Range 400
east west
linear with sill, Nugget 0.0 Sill 0.210 range 540

How to deal with something like this. I have read in the
gstat-users-manual, that the type linear with sill is only for
one-dimensional-modelling. But
which type to use then ?
How to deal with the trend. Shall I have to use universal kriging because
of the trend ? But with which model concerning the zonal anisotropy should I
use ?
Thanks for your help !
Klemens


--
Klemens Barfus
Department of Geography
University of Wuerzburg
Germany

Sent through GMX FreeMail - http://www.gmx.net

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Dear List,

I have recently obtained a BBSRC Ph.D. studentship to commence in the autumn
of 2000 at Silsoe Research Institute (Bedford, England) and the University
of Reading. I am looking for a student to take it up.

We will be using spatial analysis of data from sensor systems used in field
survey (e.g. electromagnetic inductance)for investigating soil variation at
within-field scales.  We will use geostatistical and wavelet methods for
analysis, so the student will have to be reasonably competent in mathematics
and statistics, as well as being willing to get his/her hands dirty.

University supervision will be provided by Dr Margaret Oliver, and the
student will register at the University of Reading. More details can be
found by visiting the Silsoe Research Institute website at
http://www.sri.bbsrc.ac.uk/ and following the Studentship link from the text
on the Welcome page.  I can be contacted at murray.lark@....  BBSRC
rules limit the eligibility of students who are not UK nationals.  EU
citizens must meet certain residential requirements which can be found via
the above website.

Murray Lark

**************************************

R.M. Lark

Mathematics and Decision Systems Group
Silsoe Research Institute
Wrest Park
Silsoe
Bedford, MK45 4HS
United Kingdom.

Phone: +44 (01525) 860000
Fax:   +44 (01525) 860156

**************************************

**************************************

R.M. Lark

Mathematics and Decision Systems Group
Silsoe Research Institute
Wrest Park
Silsoe
Bedford, MK45 4HS
United Kingdom.

Phone: +44 (01525) 860000
Fax:   +44 (01525) 860156

**************************************
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The Water Management Research Unit of the Agricultural Research
Service, United States Department of Agriculture is currently
recruiting for a postdoctoral research associate to analyze spatial
data from a precision farming project that was initiated in 1997.
The position is funded for at least two years.

  POSITION:  Agricultural Engineer/Hydrologist

  DESCRIPTION OF DUTIES:
  Incumbent will join a multidisciplinary team developing methodologies
  that integrate rapid, cost effective data collection with spatial
  analytic techniques to quantify variability and make spatially-variable
management
  recommendations.  Management recommendations will be implemented using
  technology which can variably apply water, nutrients, and chemicals
  within the context of irrigated precision farming.  Incumbent will
  process and review data and interact with team members to explore
  appropriate spatial data analysis techniques, perhaps to include
  multiple regression, cluster analysis, regression trees, and kriging.
  Incumbent will develop acceptable performance evaluation criteria and
  appropriate analytical procedures that can be used by consultants and
  producers to turn precision farming data into useful management
  information.

  SPECIAL REQUIREMENTS:
  PhD in Agricultural or Civil Engineering, Hydrology, Soil Science,
  Statistics, or related natural resources discipline within previous
  four years.  Demonstrated knowledge of GIS, spatial analytical techniques,
  and ability to work in a multidisciplinary team environment required.
  Familiarity with ESRI GIS software, crop production, and upscaling
  point measurements to field scale is desirable.

  The U.S. Department of Agriculture is an equal opportunity provider
  and employer.

  PLEASE SEND INQUIRIES TO:
  Dale F. Heermann
  USDA-ARS
  AERC-Colorado State University
  Fort Collins, CO 80523
  970-491-8229
email:   heermann@...
Web:  www.wmuinfo.usda.gov

------------------------------------
Lori J. Wiles
Weed Ecologist
USDA-ARS-WMU
AERC - Colorado State University
Fort Collins, CO 80523
Phone: 970-491-8520
FAX:   970-491-8247
email: wiles@...
------------------------------------

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Hi,

I am looking for a software to compute ripley's K univariate statistics
for determining if a pattern of point representing the location of trees
in a forest is random, uniform or aggregated. I also need to compute
ripley's bivariate statistic to determine if two groups of point (tree
species) are attracted or repulsed.

I know that "ads in ade-4" available at
http://pbil.univ.lyon1.fr/ADE-4/ADE-4.html can compute the univariate
statistic but the software does not include the bivariate statistic yet.
The authors told me I could get the C routines upon request. I am not
familiar with C language and would prefer using a user-friendly
software.

Any help would be appreciated.

Martin Béland
Université du Québec en Abitibi-Témisamingue
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On Tue, 21 Mar 2000, Martin Béland wrote:

> Hi,
>
> I am looking for a software to compute ripley's K univariate statistics
> for determining if a pattern of point representing the location of trees
> in a forest is random, uniform or aggregated. I also need to compute
> ripley's bivariate statistic to determine if two groups of point (tree
> species) are attracted or repulsed.
>

One possibility is Splancs (Rowlingson, B. and Diggle, P. 1993 Splancs:
spatial point pattern analysis code in S-Plus. Computers and Geosciences,
19, 627-655.) at:

http://www.maths.lancs.ac.uk/~rowlings/Splancs/

This is a library of functions for S-Plus, including both the ones you
need. I have made a port for R (see http://cran.r-project.org) for
Splancs:

ftp://reclus.nhh.no/pub/R/splancs-2.01-1.tar.gz

The "spatial" library by Venables and Ripley (the same Ripley), including
the single pattern K measure, is part of the VR bundle for both S-Plus and
R.

Hope this helps,

Roger

--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand@...
and: Department of Geography and Regional Development, University of
Gdansk, al. Mar. J. Pilsudskiego 46, PL-81 378 Gdynia, Poland.

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Hello Martin,

Have you considered the CrimeStat application available @
http://www.icpsr.umich.edu/NACJD/crimestat.html

Hope this helps,
Justin


Justin Quirouette
Regional GIS Specialist
Parks Canada Agency - Ontario Service Centre








Martin Bland <Martin.Beland@...> on 03/21/2000 10:17:51 AM

Please respond to Martin.Beland@...



  To:      ai-geostats@...

  cc:      (bcc: Justin Quirouette/Est-East/PCH/CA)



  Subject: GEOSTATS: Ripley's K functions

Hi,

I am looking for a software to compute ripley's K univariate statistics
for determining if a pattern of point representing the location of trees
in a forest is random, uniform or aggregated. I also need to compute
ripley's bivariate statistic to determine if two groups of point (tree
species) are attracted or repulsed.

I know that "ads in ade-4" available at
http://pbil.univ.lyon1.fr/ADE-4/ADE-4.html can compute the univariate
statistic but the software does not include the bivariate statistic yet.
The authors told me I could get the C routines upon request. I am not
familiar with C language and would prefer using a user-friendly
software.

Any help would be appreciated.

Martin Béland
Université du Québec en Abitibi-Témisamingue
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Could you post this, please. Thanks.

Hi..

I am struggling with an aperture data set of a fracture plane, which shows a
bimodal distribution.

I have tried Kriging and Gaussian simulation (GSLIB) to recover the aperture
structure, but it seems not to maintain both variogram and mean and variance
of the samples at the same time .

Therefore, I wonder if there is any software which is able to deal with
bimodal distribution, and
If GSLIB is a right way to go, what kind of consideration do I need and
which program is the most appropriate?

Thank you in advance..

Eunjeong..
------------------------
Eunjeng Seok
Dept. of Earth Sciences
Memorial Univ. of NFLD
St. John's, Canada
Tel: 1-709-739-7270


______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com

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Greetings,

I tried to use Splances to do K-Function computation. However, after installing
Splancs into S+4.0's library, I still cannot call the Splancs funstions in S+.

Could anyone shed lights on this issue? I deeply appreciate your help.

Guojing

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>One possibility is Splancs (Rowlingson, B. and Diggle, P. 1993 Splancs:
>spatial point pattern analysis code in S-Plus. Computers and Geosciences,
>19, 627-655.) at:
>
>http://www.maths.lancs.ac.uk/~rowlings/Splancs/
>
>This is a library of functions for S-Plus, including both the ones you
>need. I have made a port for R (see http://cran.r-project.org) for
>Splancs:
>
>ftp://reclus.nhh.no/pub/R/splancs-2.01-1.tar.gz
>
>The "spatial" library by Venables and Ripley (the same Ripley), including
>the single pattern K measure, is part of the VR bundle for both S-Plus and
>R.
>
>Hope this helps,
>
>Roger
>

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Hello,

Bimodal distributions usually indicate the
existence of two populations, and a Gaussian
approach is likely not the most appropriate.
You could try an indicator approach but don't
expect a better reproduction of histogram and semivariogram.
Note that because of the back-transform and provided
that in the normal space your simulated values follow a standard
normal distribution, the histogram of simulated sGs values
should be close to the sample histogram. Large ergodic
fluctuations (deviations between realization and
sample statistics) could be due to a large range
of the semivariogram with respect to the size of
the domain to be simulated?

If you really want to generate maps reproducing all the
statistics you mention, try simulated annealing
(sasim program in Gslib).

Pierre Goovaerts
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

   ________      ________
  |        \    /        |    Pierre Goovaerts
  |_        \  /        _|    Assistant professor
  __|________\/________|__    Dept of Civil & Environmental Engineering
|                        |   The University of Michigan
|     M I C H I G A N    |   EWRE Building, Room 117
|________________________|   Ann Arbor, Michigan, 48109-2125, U.S.A
   _|    |_\    /_|    |_
  |        |\  /|        |    E-mail:  goovaert@...
  |________| \/ |________|    Phone:   (734) 936-0141
                              Fax:     (734) 763-2275
                              http://www-personal.engin.umich.edu/~goovaert/

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>


On Wed, 22 Mar 2000, Eunjeong Seok wrote:

> Could you post this, please. Thanks.
>
> Hi..
>
> I am struggling with an aperture data set of a fracture plane, which shows a
> bimodal distribution.
>
> I have tried Kriging and Gaussian simulation (GSLIB) to recover the aperture
> structure, but it seems not to maintain both variogram and mean and variance
> of the samples at the same time .
>
> Therefore, I wonder if there is any software which is able to deal with
> bimodal distribution, and
> If GSLIB is a right way to go, what kind of consideration do I need and
> which program is the most appropriate?
>
> Thank you in advance..
>
> Eunjeong..
> ------------------------
> Eunjeng Seok
> Dept. of Earth Sciences
> Memorial Univ. of NFLD
> St. John's, Canada
> Tel: 1-709-739-7270
>
>
> ______________________________________________________
> Get Your Private, Free Email at http://www.hotmail.com
>
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> *As a general service to list users, please remember to post a summary
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>

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Dear Eunjeong Seok,

A semivariogram of a bimodal distribution reflects two kinds of variances: 1) the spatial variance between the sample points and 2) the variance between the two populations which form the bimodel distribution. The spatial variance is therefore contaminated with the variance between the two populations.

One thing you can do is try to identify the factors related to these two populations. When these factors are determined (e.g. mineral composition, direction etc. ) you can correct your data points in such a way the distribution becomes unimodal. A semivariogram of this unimodal distribution wil reflect the spatial variance with less contamination. For the new variogrammodel GSlib is appropriate.

A second way to handle the problem is simply to do two interpolations of the datapoints of the two populations separately and then subsequently combine these two interpolation results. The drawback of this method is that the number of datapoints per interpolation will be reduced.

Good luck,

Guido Ypenburg

_____________________________________________________

G.C. Ypenburg
Engenering department
Public Works Rotterdam
Hydrogeology and geostatistics
EPIV-2.22
Galvanistraat 15
PO box 6633
3002 AP Rotterdam
tel:    +31 10-489 54 97
fax:    +31 10-489 45 00

----------
Van:    Pieters, G.
Verzonden:      woensdag 22 maart 2000 8:35
Aan:    Ypenburg, G.
Onderwerp:      FW: GEOSTATS: Geostat: Program for Bimodal distribution.





----------
Van:    Eunjeong Seok[SMTP:ESEOK@...]
Verzonden:      woensdag 22 maart 2000 4:49:34
Aan:    ai-geostats@...
Onderwerp:      GEOSTATS: Geostat: Program for Bimodal distribution.
Automatisch doorgezonden door een regel

Could you post this, please. Thanks.

Hi..

I am struggling with an aperture data set of a fracture plane, which shows a
bimodal distribution.

I have tried Kriging and Gaussian simulation (GSLIB) to recover the aperture
structure, but it seems not to maintain both variogram and mean and variance
of the samples at the same time .

Therefore, I wonder if there is any software which is able to deal with
bimodal distribution, and
If GSLIB is a right way to go, what kind of consideration do I need and
which program is the most appropriate?

Thank you in advance..

Eunjeong..
------------------------
Eunjeng Seok
Dept. of Earth Sciences
Memorial Univ. of NFLD
St. John's, Canada
Tel: 1-709-739-7270




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Hello

I am way down into a paper dealing with habitat selection and spatial
distribution of territories of the Eagle Owl Bubo bubo in the East of Spain.
I am looking forward to contact anybody that may have used semivariograms
and Ripley´s K in ornithology. Being an absolute beginer in Geostatistics,
I´ll greatly appreciate comments and suggestions on my results, that will be
acknowledged in the final draft.
Thanks in advance.

Jose Antonio Martinez Climent

Departamento de Ecologia
Universidad de Alicante
Apartado 99
03080 Alicante
Spain
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Please accept my apologies for extensively cross-posting this message.
-----------------------------------------------------------------------

Hi Folks,

I've just started a mailing list for grad students and prospective grad
students in the mathematical sciences and the quantitative social sciences.
If interested, you can subscribe yourself at the URL below:

http://www.onelist.com/subscribe/EcFinMatStGradSchool


Also, if you know anyone else who might be interested in joining, please
SPREAD THE WORD!

I am in the process of trying to build a solid membership base and would
appreciate any assistance you could provide.  A description of the group
follows:


The purpose of this list is to provide a gathering place where for grad
students (and aspiring grad students) in Economics, Finance, Math,
Statistics and related disciplines.  Students in  these disciplines share
some meaningful common experiences:

a) brutal competition to get into good programs


b) grueling first-year coursework and qualifying exams often meant to
"weed-out" a significant proportion of the incoming class


c)skills, aptitudes and interests that can be easily turned to one's
advantage in the private sector (hence, serious decisions about how to
concentrate one's studies to keep all options open while maintaining an eye,
perhaps, toward the academic job market)


d)disciplinary cultures -- esp. at the grad level-- which are bit less than
"warm and fuzzy," and profs/fellow-students who may be dearly wanting in
some of the more important interpersonal skills etc.


e) research activities which are neither laboratory-based (as with the lab
sciences & engineering) nor library-based  (as with the softer social
sciences & humanities)


Ideally, this will become a vibrant forum where students from a cross-secion
of related disciplines at many different universities might share their
questions, concerns, frustrations and insights in a setting of relative
anonymity and comfort.











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Hi,

I'm a postgraduate student and I'm looking for persons who can help me to
use data, that I have had on line, in my research.

The data are presented as (x,y) pairs with : y observation and x a planar
region (so x are in R2).
My question is : "How can I reduce (x1,x2) to x if x1 and x2 are the
coordinates of my planar region?"

Thanksin advances and I hope that my english isn't too bad.

Mrs Amel KASDI
Amel@...
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Dear users,

I am not that proficient in GeoStats but rather more in GIS mapping.

I have been able to obtain a script that calculates the Jennrich
Turner Home Range (ellipse output) of a distribution of points in an
area. The output statistics of this ellipse is:
- mean of X
- mean of Y
(these will represent the unweighted centroid)
-the area
-the primary axis length
-the secondary axis length
-the angle

My question is thus this:

What does the area, the primary and secondary axis length, and the
angle indicates regarding the distribution of these points (using a
95% confidence limit)?

Any light on this will be appreciated.

Regards
Deon




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Dear netters,

I recently posted some questions to different internet lists about the
analysis of spatial point patterns for the study of competition between
jack pine and white birch and between jack pine and trembling aspen in
the boreal forest of northwestern Quebec, Canada.

Here is a summary of the questions I posted and responses I have
received (messages are ordered chronologically):
----------------------------------------------------------------------
To:   FOREST@...
Dear list members,

I am currently working on a paper on competition between jack pine and
trembling aspen and jack pine and white birch clay soils of northwestern
Quebec, Canada. I wish to use tree mapping data to estimate, for each
tree species in a stand, the intensity of competition coming from each
species. I want to do this for the whole stand and for a few target
trees.

My question is :  Do some of you know of a method of analysis of spatial
pattern and computer program that can account for mixed stands. I am not
very familiar with this type of analyses. I have found one program on
the internet, called ADS in ADE4, but couldn’t figure out yet if tree
species can be differentiated.
---------------------------------------------------------------------------
   From:  voyteck.zakrzewski@...
> Suggest two people to contact: Dr. S. Titus or/and  Dr. Stan Navratil
(try
> at University of Alberta in Edmonton).
---------------------------------------------------------------------
From:  "Norm Cimon" <ncimon@...>
Have you thought of nearest neighbor analysis?  One way to examine the
potential competition would be look at the variations in clustering
between
the different species.  Nearest neighbor techniques determine whether or
not a distribution pattern is random, and there are computer programs in
the
public domain to perform the computations.  For more information,
contact Andy Younblood (ayounbl/r6pnw_lagrande@...).
-----------------------------------------------------------------------
From: Jacques_Begin <jacques.begin@...>
Salut Martin.  Je te suggere de parler a Kim Lowell ou a Geoffrey
Edwards
418 656 5491 de la Chaire industrielle en geomatique.  Ils ont developpe
une application pour l'identification individuelle des cimes a partir de
l'algorithme de Voronoi, si je ne me trompe pas.

Bonne chance et donne m'en des nouvelles
-----------------------------------------------------------------------
From: Phil Carter <PhilC@...>
A couple of years ago I did some work on inter tree competition. I used
a
tree map in a GIS (Arc/Info) to give me information on the spatial
characteristics of the stand.

Basically, I used Arc/Info to identify the competitors of each tree,
then
applied different definitions of "competitor" to study the different
competition indices. I used 2 approaches:

The Arc/info POINTDISTANCE command computes the distance between point
features in one coverage to all points in a second coverage. If these 2
coverages are the same, you get all possible combinations in a single
file,
and you can select out what you need.

The BUFFER command identifies a zone of a specified width around a
specified
feature. Obviously, if the feature is a point, the buffer is circular.
Buffer radius was a function of tree diameter at breast height. With the
Arc/Info version I was using at the time (6 years ago), I could not
specify
different buffer sizes on the same cover, so I had to write an Arc macro
that selected each one of my sample trees in turn, calculate a buffer
size,
then clip this buffer out of the stand map. This gave me a sample of
trees
inside a known distance from each sample tree.

Arc/Info will also give you Thiessen polygons.

My analysis didn't go as far as identifying individual species, but it
would not be too difficult to identify tree species in you tree map.

Hope this helps.
-----------------------------------------------------------------------
Martin, vous pouvez contacter François A. Gougeon dans le Pacific Forest
Centre (http://www.pfc.forestry.ca). Je vous acompagne une page web avec
laquel vous pouvez decider si ça c'est d'interest pour vous.
Merci bien
-----------------------------------------------------------------------
From:       dan.duckert@...
The only tree mapping program I have used is SVS or SVS2 (Stand
Visualisation Simulation). It was produced out of University of Oregon
Corvallis. I haven't used it for a number of years. I am sure they have
a
web site and possibly freeware. Good luck.
-----------------------------------------------------------------------
From:  "West Family" <dwest@...>
Most GIS systems are capable, with addin software, of doing spatial
analysis. While GIS is used for mostly large scale mapping applications
it can be used at smaller scales. We have used our GIS to map and
analysis individual trees in our seed orchard. You should be able to use
it to analyses trees in a stand.
-----------------------------------------------------------------------
From:        Alain Leduc <r13064@...>
Moeur, M. 1993. Characterizing spatial patterns of trees using
stem-mapped
data. Forest Science 39: 756-775.

Moeur, M. 1995. Ripley's K analysis program. U.S. Dep. of Agriculture,
Forest Service, Intermountain Research Station, Moscow, Idaho.
-----------------------------------------------------------------------
From:             guest <alister/ne_fia@...>
Hi!  Saw your note in the FIU.  Try the ai-geostats homepage (do a net
search for ai-geostats).  If you get there, go to the soft-faq, where
there is tons of free software that can be used to analyze spatial point
patterns.  One thing that occurs to me from your description is analyses
of spatial dependence and joint spatial dependence, via
variograms/covariograms, etc.  The softfaq has a search tool.  You
should also join the ai-geostats discussion list, and ask your question
to the group.

Another idea--look at the spatial dependence of similarity (like in
cluster analysis--Euclidean distance, or something like that---using a
variogram-like procedure.  How does similarity of vegetation quadrats
change with increasing or decreasing distance apart?

Good luck.
-----------------------------------------------------------------------
From:         Pius Hauenstein <Pius.Hauenstein@...>
I read about your problem of estimating the competition between jack
pine, trembling aspen and white birch in the FIU  of Feb. 14 2000.
I'm not the "absolute specialist" in tree competition, but I made some
investigations about forest structure with a spatial approach. While
searching for good literature I have seen some articels, which have
competition as main task. During my work (Ph D thesis) I learnd a lot
about the principle problems of  analysing the structure of a forest. So
I think studies of competition are "only" a special case of structural
analysis. In the attachment you will find some reflection about this
theme. This paper is not published, but you can use it. Please make a
cititaion to the original work (You will find it under my name in the
the references).
The second attachment contains a list of titles about your theme, which
I found after a short search in my personal literature database. Some of
them are written in german ... . I inserted only the most important.

I hope my information gives you a little help. Finaly, I'm interested in
your results, please let me know.

Best regards
-----------------------------------------------------------------------
To:             adelist@...
Bonjour,

J'aimerais savoir si ads peut calculer les fonctions bivariées L(d)
permettant d'étudier le lien entre deux groupes (exemple: espèce
d'arbres) de points.

In English:
I would like to know if ads can compute Ripley's bivariate functions to
estimate the dependance between to groups of points (tree species).
-----------------------------------------------------------------------
From:         Goreaud Francois <francois.goreaud@...>
     To:   adelist@...,
Translated in English:
-> Yes, it is easy to compute intertype functions L1.2(d), which
characterize the spatial structure of qualitative marks (i.e. species).

-> The corresponding routines are for the moment available in C upon
request

-> They should soon be integrated in a new module in ADS...
-----------------------------------------------------------------------
From:             Martin Béland <Martin.Beland@...>
To:            ai-geostats@...

Hi,

I am looking for a software to compute ripley's K univariate statistics
for determining if a pattern of point representing the location of trees
in a forest is random, uniform or aggregated. I also need to compute
ripley's bivariate statistic to determine if two groups of point (tree
species) are attracted or repulsed.

I know that "ads in ade-4" available at
http://pbil.univ.lyon1.fr/ADE-4/ADE-4.html can compute the univariate
statistic but the software does not include the bivariate statistic yet.
The authors told me I could get the C routines upon request. I am not
familiar with C language and would prefer using a user-friendly
software.

Any help would be appreciated.
-----------------------------------------------------------------------
From:            Baz <B.Rowlingson@...>
  I have code to do this with edge corrections on a polygon. Its part of
my 'splancs' library for S-plus, so you'll have to unwrap the relevant
code
yourself. Its in fortran.

  Download the unix source code release from:

http://www.maths.lancs.ac.uk/~rowlings/Splancs
-----------------------------------------------------------------------
From:          Roger Bivand <rsb@...>
Reply-To:          Roger.Bivand@...

One possibility is Splancs (Rowlingson, B. and Diggle, P. 1993 Splancs:
spatial point pattern analysis code in S-Plus. Computers and
Geosciences,
19, 627-655.) at:

http://www.maths.lancs.ac.uk/~rowlings/Splancs/

This is a library of functions for S-Plus, including both the ones you
need. I have made a port for R (see http://cran.r-project.org) for
Splancs:

ftp://reclus.nhh.no/pub/R/splancs-2.01-1.tar.gz

The "spatial" library by Venables and Ripley (the same Ripley),
including
the single pattern K measure, is part of the VR bundle for both S-Plus
and
R.
-----------------------------------------------------------------------
From:             "Russell Cole" <r.cole@...>
I've got, but haven't tried, a prog by DongMei Chen & Art Getis
called PPA. Prof. Getis sold me a copy for US$15. It's written &
compiled in C.
It does: nearest neighbour, refined nearest neighbour, K-function,
weighted K-function, space-time Knox (no idea), Join-Count
statistics, Global Moran's I & Geary's C, general Getis-Ord's G,
local moran's I(d), local G(d) & G(d)*, and local K-function. It looks
pretty simple.

Try him at: Dept of Geography, San Diego State Uni, San Diego,
CA92118-4493, USA. email arthur.getis@....
-----------------------------------------------------------------------
From:         Justin_Quirouette@...

Have you considered the CrimeStat application available @
http://www.icpsr.umich.edu/NACJD/crimestat.html

Hope this helps,
Justin
-----------------------------------------------------------------------
From:         Norm Finkelstein <finkelst@...>

The short answer is S-PLUS software with its S-Plus Spatial Stats
module.

Two more points:

1) if you just might have to work with non-rectangular bounding
region(s);
2) if you want to analyse the processes both in time and space,

it would be a good idea to obtain an S-PLUS' library of functions called
SPLANCS from Lancaster U. in the UK.

I have referred a couple of researchers to that URL in the last couple
of
years and they seemed to be pleased with SPLANCS' capabilities, as am I.
I am including below their summaries to the list on the subject (they
contain the URL) in lieu my directions and descriptions anew.

Best of luck,
-----------------------------------------------------------------------
From:            Lisa Cuthbertson <lcuthber@...>

John Brzustowski at the University of Alberta (Edmonton, Canada) has
written a program called Potemkin that has Ripley's K (univariate and
bivariate
point patterns) within it.  He uses Haase's  edge correction (1995) and
I think you
can choose the wrap around edge correction as well. John has many other
programs that may be useful and if you do a search for John
Brzustowski's
Programs you should find the page.  I copied some of the potemkin page
(see
below).  I hope this helps.

Potemkin, very preliminary, is a front end for making command line
programs
look prettier to the user under Win95.

It currently has a simple table-editor that reads and writes
TAB-delimited
text, and allows you to glue several files together, as well as to
selectively hide rows and/or columns. The data visible in the table can
be
saved, or sent to other programs, whose output appears in a window.

Current features:

calculate distances and perform clustering between rows or columns of a
table merge rows or columns that have the same values in certain cells
e.g. merge
all rows having the same values in columns 1 and 2. Merged values can be
the sum, mean, min, or max of the values in the merged columns or rows.
export data in Cornell condensed format, suitable for either Canoco or
Twinspan. compute Ripley's K(t) index of spatial point pattern variance

More to come...
Potemkin is free software. You can download the self-extracting
executable
from: ftp://www.biology.ualberta.ca/pub/jbrzusto/potemkin/potzip.exe

To install it, create a new directory where you want to store the
program,
put potzip.exe in it, and run it there. Once it has extracted itself,
you
can delete potzip.exe To run the program, execute potemkin.exe

Source code (for Borland C++ Builder) is available in
ftp://www.biology.ualberta.ca/pub/jbrzusto/potemkin/potsrc.zip

Please send any feedback to John Brzustowski at
jbrzusto@.... There are more free programs at
http://www.biology.ualberta.ca/jbrzusto

This http link doesn't work so you'll have to do a search for John B
like I
said above!

Hope this helps!
-----------------------------------------------------------------------
From:         Søren Ring Ibsen <SOERENRI@...>

Hello Martin Biland

What a coincidense - I'm looking for the same thing, that is a user
friendly free Software for calculating Ripsleys K-function. Please let
me
know if you find any useable solution. I will of course tell you if I
find
some.

Are you doing semivariance analysis on your tree-coordinate data as
well?

If yes - then have a look at:
http://www.metla.fi/silvafennica/SF-Abstracts/sa302315.htm
<http://www.metla.fi/silvafennica/SF-Abstracts/sa302315.htm>

Here is some of it:

"Silva Fennica abstract

Kuuluvainen, T., Penttinen, A., Leinonen, K. & Nygren, M. 1996.
Statistical
opportunities for
comparing stand structural heterogeneity in managed and primeval
forests:
An
example from
boreal spruce forest in southern Finland. Silva Fennica 30(2-3):
315-328.

      The horizontal and vertical stand structure of living trees was
examined in a managed and in a primeval spruce-dominated forest in
southern
Finland. Tree size distributions (DBHs, tree heights) were compared
using
frequency histograms. The vertical distribution of tree heights was
illustrated as tree height plots and quantified as the tree height
diversity
(THD) using the Shannon-Weaver formula. The horizontal spatial pattern
of
trees was described with stem maps and quantified with Ripley's
K-function.
The spatial autocorrelation of tree sizes was examined with
semivariogram
analysis. In the managed forest the DBH and height distributions of
trees
were bimodal, indicating a two-layered vertical structure with a single
dominant tree layer and abundant regeneration in the understory......."


Best regards
-----------------------------------------------------------------------
From:         "Gaston Pezzuchi" <gpezzuchi@...>

I would suggest you try to use the CrimeStat Software available at:
www.icpsr.umich.edu/NACJD/Crimestat.html

It is a really great program if you wish to perform spatial statistical
analysis of point incidents...

The Ripley's K function can be easily calculated and it works great with
most of GIS packages....

On the Other hand its manual is really impressive and self explanatory

hope it helps
-----------------------------------------------------------------------
From:             Martin Béland <Martin.Beland@...>
          To:      jbrzusto@..., jbrzusto@...

Dear Mr Brzustowski,

I have downloaded your software called Potemkin from
ftp://www.biology.ualberta.ca/pub/jbrzusto/potemkin/potzip.exe. I have
succeeded in importing my data files in the data sheet and tried to
perform Ripley's K function on xy coordinates. I want to use these
statistics to study competition in forests stands composed of mixtures
of jack pine
and trembling aspen or white birch. The data I have come from square 20
m by 20 m plots.

It doesn't seem to work. The message I get in the output window is the
following:

> kindex TMP1.$$$ -rb square 20 20 100 0.05
*** Error:

I wonder:

Is the program still under development or is it supposed to be working
properly?
Do you have a help file or instructions for use of this software?
Do you have a description of the edge effect correction used?
Does the program need decimals to be , or . ?
How do the species data need to be entered: characters or numerals?
I guess the units of measurement for xy coordinates and study area size
don't matter if they are the same?

Thank you very much in advance for your help.
-----------------------------------------------------------------------
From:         John Brzustowski <jbrzusto@...>
Hello, Martin

  > It doesn't seem to work. The message I get in the output window is
the
  > following:
  >
  > > kindex TMP1.$$$ -rb square 20 20 100 0.05
  > *** Error:

There may be a problem with the setup.  Is potemkin installed in a
directory called "c:\Potemkin"?  Potemkin is not very smart,
especially about that kind of thing.

  > Is the program still under development or is it supposed to be
working
  > properly?

What's there is supposed to work, but I'm not actively developing it -
I don't use Windows any more.  I will try to fix bugs, though.

  > Do you have a help file or instructions for use of this software?

Unfortunately not - it was supposed to be fairly straightforward to use,
but
that doesn't seem to be the case.  There aren't any hidden features or
options that would affect what you're trying to do.

  > Do you have a description of the edge effect correction used?

For points too close to the edge for their circular neighbourhood to
lie entirely within the sampling region, the count of points within
that neighbourhood is scaled, although in a slightly funny way, by
circumference rather than area. (e.g. if only half the neighbourhood
is within the sampling region, the count there gets doubled)
Here's the math, from the source code (kindex.c):

    The index K(t) is given by:

   A / n    * sum (I   (u  ) / w  )
        i,j         t    ij     ij


    where  I (x) = 0 if x > t, else 1
            t

    u   = distance between points i and j
     ij


    w   = fraction of circumference of circle of radius u   centred at
sample
     ij                                                  ij

    point i that lies within the sampled region

    see:  Andersen, M.  (1992)  Spatial analysis of two-species
interactions.
    Oecologia 91:134-140.

  > Does the program need decimals to be , or . ?

Decimals as '.'  e.g. 2.123  2.3451

  > How do the species data need to be entered: characters or numerals?

Species should be coded as '1' or '2' for the bivariate K function.

  > I guess the units of measurement for xy coordinates and study area
size
  > don't matter if they are the same?

The calculations implicitly assume all
measurements are in comparable units, but it doesn't matter what they
are.  So the unit of area should be the square of the unit of length.
(e.g. m^2 and m)

  >
  > Thank you very much in advance for your help.
  >

Il n'y pas de quoi.  Tant que j'espère que ce logiciel vous soit util,
je suis de l'avis que vous auriez plus de succès en utilisant le
language "R", un logiciel libre/gratuit qui remplace "S+".  Il y a
dedans un ensemble de statistiques spatiales, où se trouve la fonction
"K"
de
Ripley, parmi d'autres.

Si ça vous intéresse, "R" se trouve ici:

ftp://sunsite.ualberta.ca/pub/Mirror/CRAN/bin/windows

Bien sûr, ça n'a pas l'aire aussi amicable que Potemkin, mais c'est un
vrai ensemble de logiciels pour statistiques, utilisé partout, et vaut
bien la peine d'apprendre (je m'excuse si je vous raconte des choses
bien connues!)

Bonne chance!
-----------------------------------------------------------------------
Hello John,

Thanks for your prompt answer!! Don't worry, you are telling me nothing
I already knew!

After moving the program to the root of C:, it seems to work! However I
still have two questions for you:

First, after running the program with some of my data, I am surprised to
see values of K(t) that are very high. From the readings I have done in
the literature, I thought that K(t) should have a max value of 1?

Secondly, I thought that bivariate analysis of interaction between
species 1 and 2 should be the same as that of interaction between
species 2 and 1. The output given by potemkin for the bivariate analysis
includes K1,1 K1,2 K2,1 and K2,2. The values for K1,2 and K2,1 for short
values of t are the same but as t increases, K2,1 becomes larger that
K1,2. The confidance intervals are different from the beginning.

I would greatly appreciate your help on these two questions.

-----------------------------------------------------------------------
Martin Béland
Université du Québec en Abitibi-Témiscamingue
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Dear netters,

I have a question regarding offshore natural oil seep detection.
What kind of imagery can we use in detecting natural oil seep ?

Regards

MINARWAN
+62-21-7182001 ext. 5629


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About two months ago I posed a question to the listserver, to help in our
spatial analysis of roadkills along the Trans-Canada Highway in Banff National
Park.  Here is a long overdue summary of the responses I received.

Question:

Hi I am working on a research project that studies roadkills on the Trans-Canada
Highway, a linear vector spanning over 141 miles.  I am looking at hotspots, or
clusters of roadkills along the highway, from small to large mammals.   I am
starting with a simple analysis that looks if the  kills are related to the
access points, (breaks in the wildlife fence).  Firstly, I was wondering if
someone knows a script that I can use that puts random points on my linear
vector, so I can look at a Chi-square test or Hines test for randomness. (Do I
need random points along the line vector or would a ploygon suffice?) Also once
I have tested for clusters, or aggregation, how do I link these clusters to the
access points.  I am looking at a simple two step analysis, for testing for
clusters, and are these clusters related to the access points.  It would be
great if someone could lead me in the right direction..............

Thanks Kari


Response 1:

You might want to look at "local statistics" and K functions. The journal
Geographical Analysis
has a number of articles on the subject.

Art Getis

Response 2:

1.  If you will test against differences between two distributions, then both
your distributions must be comparable.  Therefore you need random points on your
linerar vector.

2.  Is the highway absolutely linear like a line between two points?  In this
case you can use a simple worksheet function for random number generation like
in Excel.  For testing you should only compare the coordinates of one axis
(west-east or north-south), its useful to choose the axis with the greatest
extend.

3.  If the highway is not absolutely linear you can make a workaround.  First
you should make a buffer around your highway with a  very small distance/radius.
After buffering use a random number generator for polygons.  For ArcView exists
a simple script, which you can find on the ESRI-Website:  http://www.esri.com.
Because the lateral extension of the buffer is very small I think you can
neglect it in all cases where you will find very great differences between both
the distributions.  For testing you should only compare the coordiantes of one
axis (west-east or south-north), its useful to choose the axis with the greatest
extend.

4.  To link the clusters with your access points you can go in different ways.
For instance you can make buffers with a defined radius around your access
points and do an identity operation.  You will find some tools in Atlas*GIS
(access points) or ArcView (XTools-Extension, Animal Movement Extension; both
you can find on ESRI's site).  I think the Animal Movement Extension is very
useful for your aims.

5.  I think the best way to compare your distributions is to perform a
nearest-neighborhood analysis between your access points and the road kills
compared with the nearest neighborhood distances between your access points and
the random points.

hope this helps
Reinhard
Dr. Reinhard Klenke
Society for Nature Conservation and Landscape Ecology (GNL)
phone 49-39822-20 474
fax:  49-39822-20 474

Response 3:

Hi Kari,

I'm not really an expert in spatial statitics but it seem to me that you might
apply the Ripley's K statisitcs to your data.  I recomment you to take a look
athe following article:

O'Driscoll, R.L. 1998.  Description of spatial pattern in seabird distributions
along line transects using neighbour K statistics. Mar. Ecol. Prog. Ser.
165:81-94.

Also Boots, B.R. and A. Getis. 1988.  Point Pattern Analysis. SAGE publications.
give some examples of the application of measures of dispersion in one
dimension.  As for the software, well the only one I know is available is the
S-plus and you have to add the libraries Splancs and Spatial.  THere is a
student version of S-plus for a little less than $100 dollars and libraries can
be downloaded from the internet.  However, I am not sure if you can use the
software for one dimentsion directly, most likely you might need to make some
modifications and obviously you will need to study the S-plus language for that.
Anyway, hope this informations is of some help to you. Good luck,

Jose Alcantara
School of Forestry, Wildlife and Fisheries
Louisiana State University
Baton Rouge, La.

Response 4:

First of all numbers from a uniform (0,1) random number generator can be mapped
onto any stretch of highway.  With as many points from the random generator as
there are road kills you can then create two empirical distributions and test
for their being the same with the Kolmogorov-Smirnov statistic.  This will
simply tell you that the road kills are (not) from a uniform distribution along
the highway.

You actually do not have to generate the points.  The cumulative distribution
along the highway has a slope of 1/L, where L is the length of the highway
segment.  i.e. F=x/L, 0<=x<=L.  Now make an empirical distribution of the
roadkills and use the K-S one sample test statistic.

You may also look at gap sizes and their distribution to obtain a 'best' Pearson
type distribution for waitng times, except your waiting time is simply the
distance between kills.

You may also divide the road into a set of segments and fill in the counts for a
one dimensional contingency table.

Lastly, you can use the scan statistic found in CLUSTER, CLUSTER can be
downloaded from CDC/ATSDR.

Send me your data, and I will find an unwilling student to have a look at them.
I wrote CLUSTER along with three others.

Sincerely yours,

Wanzer Drane
Professor of Biostatistics
USC School of Public Health, 205
Columbia, SC 29208
803-777-5053

Response 5:

Which software are you using for the analysis?  I can give you some hints on
Avenue (ArcVIew script language) and S+, although I have no premade script.
Shouldn't be too difficult, though.

You can just transform all your observation in distances from the starting point
in the hwy, and then you just have to draw a random number.

BTW, where on the Hwy are you working?  Is it the Banff stretch?

Marco Albani
PhD Candidate
Dept. of Forest Sciences - UBC



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Dear netters,

I recently posted a summary of questions and responses about analyses of
point patterns to study competition in mixed jack pine stands. Here is
one more question that arose from running the software called
"Potempkin" to compute intertype Ripley's K(d) analysis :

I thought that bivariate analysis of interaction between species 1 and 2
should be the same as that of interaction between species 2 and 1. The
output given by potemkin for the bivariate analysis includes K1,1 K1,2
K2,1 and K2,2. The values for K1,2 and K2,1 for short values of d are
the same but as d increases, K2,1 becomes larger that K1,2. The
confidance intervals are different from the beginning. How do you
explain this?

To this, John Brzustowski, the author of the programm replied to me

> Good question.  I don't seem to have a paper describing the bivariate
> K here, but what I think is happening is this:
> The obvious definition for bivariate K(t) would be the proportion of
> pairs of individuals, the first of species 1, the second of species 2,
> that lie within a distance t or less of each other.  That would give a
> symmetric definition.  But I think Ripley does this a bit differently:
> K1,2 (t) is the average, over all individuals in species 1, of the
> proportion of species 2 neighbours that are within distance t of the
> individual in species 1.  This is a bit tricky, but it just amounts to
> weighting the pairs differently in each case.  I suppose an advantage
> of this approach is it should allow one to detect attraction of
> species 1 by species 2, as opposed to the other way around. Maybe.
>

Does any of you know:
1- if other software compute the bivariate K(t) in a different way that
use a symmetric definition of the interaction? and
2- if there is no other way to compute the bivariate K(t), how do you
suggest the result must be interpreted, that is, which of K1,2 or K2,1
must be used in which situation?

Any help would be appreciated,


Martin Béland, biologiste, Ph.D. Env.
Unité de recherche et de développement forestiers de
l'Abitibi-Témiscamingue
Université du Québec en Abitibi-Témiscamingue
445, boulevard Université
Rouyn-Noranda (Québec) J9X 5E4
Téléphone : (819) 762-0971 #2458
Fax : (819) 797-4727
Courriel : martin.beland@...
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*****************************************
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Dear all,

I have two questions.

The first one is about the use of cross-validation, jacknife and bootstrap in
geostatistics while developed for independent and identically distributed
observations. What are the consequences of the application of these techniques
to dependent data and what can be done to adapt these techniques to
geostatistics.

My second question is about the nugget effect, which can be defined as

Nugget Effect (NE) = Error Variance (EV) + Micro Variance (MV) ,

where the error variance is the variance of the measurement errors, and the
micro variance is the variance of the small scale structure.

This definition is the one implemented in Surfer and follows the
recommendation of Cressie

CRESSIE N. (1993)
Statistics for spatial data
John Wiley & Sons Inc. (Revised Edition)
(see pages 127 - 130)

When EV = 0 and NE > 0, the estimates will honor every observation,  when MV =
0 and NE > 0, the estimates do not honor every observation. Both situations
will have a smoothing effect.

I have made a few tests to evaluate the relative impact of both components but
could not see differences between EV and MV. For a given value of the NE and
for different combinations of EV and MV, I always get the same estimates. Does
anyone have an explanation for that ?

I couldn't find any references to publications where both components are
quantified in a case study and would welcome any suggestions.

Thank you for any help

Gregoire



Gregoire Dubois
Section of Earth Sciences
Institute of Mineralogy and Petrography
University of Lausanne
Switzerland

Currently detached in Italy

http://curie.ei.jrc.it/ai-geostats.htm

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Dear geostats,

I am currently writing an article, using techniques
of interpolation.

Although I must clarify the original source
(e.g. book, paper) of IDW, I cannot
find one.  This must be a very old technique, isn't it?

If anybody knows who invented IDW and what
was the first publication on this, please let
me know any minute information relevant to it.

Your attention would be appreciated.

Yoshiro Nagao
London School of Hygiene and Tropical Medicine

______________________________________________________
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