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#2430 From: "Huybert Groenendaal" <huybert@...>
Date: Fri Oct 23, 2009 3:38 am
Subject: RE: [CBUG] Path Dependent simulations in CB
huybert
Offline Offline
Send Email Send Email
 
Hi Dan,



Doing path-dependent simulations with CB is typically fairly
straightforward. For example, employee-stock options nowadays frequently
only vest if the stock has met certain conditions before expiration. So, if
at expiration the price is $20, it actually depends on the path (i.e.
price-trajectory) the stock price went through what the actual value of the
option is. Frequently, the most efficient way to incorporate these sorts of
path dependencies is with simple logical statements in Excel (e.g. the IF,
AND, MAX, MIN, and other statements).



Best wishes,

Huybert



From: cbug2@yahoogroups.com [mailto:cbug2@yahoogroups.com] On Behalf Of
dansch_1998
Sent: Thursday, October 22, 2009 7:07 AM
To: cbug2@yahoogroups.com
Subject: [CBUG] Path Dependent simulations in CB





I am trying to create a simulation that is path-dependent
(forecast/assumption value #612 in year 5 depends on forecast/assumption
value #612 for years 1 through 4). Other than extracting all assumption
trial values and manually calculating the forecasts (which results in
unwieldly massive workbooks) does anyone see how this can done in CB?

Much obliged!





[Non-text portions of this message have been removed]

#2431 From: "dansch_1998" <dan.schneider@...>
Date: Sat Oct 24, 2009 6:54 pm
Subject: Re: [CBUG] Path Dependent simulations in CB
dansch_1998
Offline Offline
Send Email Send Email
 
Thanks--I'm not sure if the stock-option example will work in my case. I'm
running a garch model where the current year's volatility is a function of the
prior 10 periods' volatility--I have a set of 10 garch factors that I'm using in
a sumproduct function, but it requires that all of the volatilities fall in the
same path.
I can do this using cb.normal functions in each cell, but if I want to run 3000
threads for 100 periods, the files get huge and unwieldy.


--- In cbug2@yahoogroups.com, "Huybert Groenendaal" <huybert@...> wrote:
>
> Hi Dan,
>
>
>
> Doing path-dependent simulations with CB is typically fairly
> straightforward. For example, employee-stock options nowadays frequently
> only vest if the stock has met certain conditions before expiration. So, if
> at expiration the price is $20, it actually depends on the path (i.e.
> price-trajectory) the stock price went through what the actual value of the
> option is. Frequently, the most efficient way to incorporate these sorts of
> path dependencies is with simple logical statements in Excel (e.g. the IF,
> AND, MAX, MIN, and other statements).
>
>
>
> Best wishes,
>
> Huybert
>
>
>
> From: cbug2@yahoogroups.com [mailto:cbug2@yahoogroups.com] On Behalf Of
> dansch_1998
> Sent: Thursday, October 22, 2009 7:07 AM
> To: cbug2@yahoogroups.com
> Subject: [CBUG] Path Dependent simulations in CB
>
>
>
>
>
> I am trying to create a simulation that is path-dependent
> (forecast/assumption value #612 in year 5 depends on forecast/assumption
> value #612 for years 1 through 4). Other than extracting all assumption
> trial values and manually calculating the forecasts (which results in
> unwieldly massive workbooks) does anyone see how this can done in CB?
>
> Much obliged!
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

#2432 From: "blankind" <djb@...>
Date: Sun Oct 25, 2009 4:43 pm
Subject: Re: OPTQUEST - ENTERING REQUIREMENT DECIMAL
blankind
Offline Offline
Send Email Send Email
 
Assuming that you are using the most recent version of Crystal Ball
(11.1.1.3.00), the workaround for this issue is easy.  The formatting of the
righthand side of the requirements expression is based on the format of the
associated forecast cell.  In your case, you are likely referring to a forecast
that has x.yy formatting (decimal value with 2 points to the right of the
decimal).  To be able to properly handle the value of 0.00665, you would need to
change the cell format for that forecast cell to be x.yyyyy (decimal value with
5 points to the right of the decimal).  Now, there is a bit of a truncation
issue with the entered value has more decimal precision that the forecast cell's
format and I have just logged that as an issue under consideration to be fixed
in the next release.

Sincerely,
David Blankinship
Manager, Quality Assurance
Crystal Ball Application
Oracle

--- In cbug2@yahoogroups.com, "eyunda" <eyunda@...> wrote:
>
> I apply OptQuest>Objetives>Add Requirement> The "Mean" of "C95" must be
"greater than" 0,00665.
>
> Suddenly OptQuest apply 0,00, but not 0,00665.  How to solve it?  I would
appreciate your comments.
>

#2433 From: "Huybert Groenendaal" <huybert@...>
Date: Sun Oct 25, 2009 4:01 am
Subject: RE: [CBUG] Path Dependent simulations in CB
huybert
Offline Offline
Send Email Send Email
 
You're welcome. I see your point. We've done GARCH models with CB, but not
with looking back 10 periods to determine this year's volatility. Hope
others on the list will be able to help!

Huybert



From: cbug2@yahoogroups.com [mailto:cbug2@yahoogroups.com] On Behalf Of
dansch_1998
Sent: Saturday, October 24, 2009 12:54 PM
To: cbug2@yahoogroups.com
Subject: Re: [CBUG] Path Dependent simulations in CB





Thanks--I'm not sure if the stock-option example will work in my case. I'm
running a garch model where the current year's volatility is a function of
the prior 10 periods' volatility--I have a set of 10 garch factors that I'm
using in a sumproduct function, but it requires that all of the volatilities
fall in the same path.
I can do this using cb.normal functions in each cell, but if I want to run
3000 threads for 100 periods, the files get huge and unwieldy.

--- In cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com> , "Huybert
Groenendaal" <huybert@...> wrote:
>
> Hi Dan,
>
>
>
> Doing path-dependent simulations with CB is typically fairly
> straightforward. For example, employee-stock options nowadays frequently
> only vest if the stock has met certain conditions before expiration. So,
if
> at expiration the price is $20, it actually depends on the path (i.e.
> price-trajectory) the stock price went through what the actual value of
the
> option is. Frequently, the most efficient way to incorporate these sorts
of
> path dependencies is with simple logical statements in Excel (e.g. the IF,
> AND, MAX, MIN, and other statements).
>
>
>
> Best wishes,
>
> Huybert
>
>
>
> From: cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com>
[mailto:cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com> ] On Behalf
Of
> dansch_1998
> Sent: Thursday, October 22, 2009 7:07 AM
> To: cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com>
> Subject: [CBUG] Path Dependent simulations in CB
>
>
>
>
>
> I am trying to create a simulation that is path-dependent
> (forecast/assumption value #612 in year 5 depends on forecast/assumption
> value #612 for years 1 through 4). Other than extracting all assumption
> trial values and manually calculating the forecasts (which results in
> unwieldly massive workbooks) does anyone see how this can done in CB?
>
> Much obliged!
>
>
>
>
>
> [Non-text portions of this message have been removed]
>





[Non-text portions of this message have been removed]

#2434 From: Edgar Yunda <eyunda@...>
Date: Mon Oct 26, 2009 7:17 pm
Subject: Re: [CBUG] Re: OPTQUEST - ENTERING REQUIREMENT DECIMAL
eyunda
Offline Offline
Send Email Send Email
 
Thank you David, your solution is clear and it really works.  Edgar

--- El dom, 25/10/09, blankind <djb@...> escribió:

De: blankind <djb@...>
Asunto: [CBUG] Re: OPTQUEST - ENTERING REQUIREMENT DECIMAL
Para: cbug2@yahoogroups.com
Fecha: domingo, 25 octubre, 2009 11:43






 





                   Assuming that you are using the most recent version of Crystal
Ball (11.1.1.3.00) , the workaround for this issue is easy.  The formatting of
the righthand side of the requirements expression is based on the format of the
associated forecast cell.  In your case, you are likely referring to a forecast
that has x.yy formatting (decimal value with 2 points to the right of the
decimal).  To be able to properly handle the value of 0.00665, you would need to
change the cell format for that forecast cell to be x.yyyyy (decimal value with
5 points to the right of the decimal).  Now, there is a bit of a truncation
issue with the entered value has more decimal precision that the forecast cell's
format and I have just logged that as an issue under consideration to be fixed
in the next release.



Sincerely,

David Blankinship

Manager, Quality Assurance

Crystal Ball Application

Oracle



--- In cbug2@yahoogroups. com, "eyunda" <eyunda@...> wrote:

>

> I apply OptQuest>Objetives> Add Requirement> The "Mean" of "C95" must be
"greater than" 0,00665.

>

> Suddenly OptQuest apply 0,00, but not 0,00665.  How to solve it?  I would
appreciate your comments.

>































[Non-text portions of this message have been removed]

#2435 From: "Ian" <ianmagee@...>
Date: Tue Oct 27, 2009 3:13 pm
Subject: out of memory error when extracting data
ian_magee
Offline Offline
Send Email Send Email
 
Hi,

I'm getting an out of memory error when trying to extract the data from a run, I
only started getting these recently.  It performs the run OK but then will not
let me extract the data.  The actual error message text is "Unable to complete
extract data due to:  Unable to complete  due to:  Exception of type
'System.OutOfMemoryException' was thrown."

Can anyone help with this?

Thanks,
Ian Magee

#2436 From: "blankind" <djb@...>
Date: Wed Oct 28, 2009 1:54 pm
Subject: Re: out of memory error when extracting data
blankind
Offline Offline
Send Email Send Email
 
Ian,

This error message is a system-level out-of-memory message, so you might want to
look at the length of the simulation you are running, the size of the data
extract, etc., to minimize memory use.  Crystal Ball does its own memory
assessments prior to intensive operations such as optimizations and simulations,
but this is not performed for all commands and you could be encountering this
type of situation with the Extract Data call.  If you refer to the Crystal Ball
log file at:

%appdata%\Oracle\Crystal Ball\11.0\Logs

you can look at the end of the log file to get a bit more logging information
(including possibly some memory state information) right before the unexpected
error occurred.  Note that the %appdata% in the path is a system variable and
maps to C:\Documents and Settings\<username>\Application on Windows XP.

Sincerely,
David Blankinship
Manager, Quality Assurance
Crystal Ball Application
Oracle

--- In cbug2@yahoogroups.com, "Ian" <ianmagee@...> wrote:
>
> Hi,
>
> I'm getting an out of memory error when trying to extract the data from a run,
I only started getting these recently.  It performs the run OK but then will not
let me extract the data.  The actual error message text is "Unable to complete
extract data due to:  Unable to complete  due to:  Exception of type
'System.OutOfMemoryException' was thrown."
>
> Can anyone help with this?
>
> Thanks,
> Ian Magee
>

#2437 From: "jamesamurtha" <jmurtha@...>
Date: Wed Oct 28, 2009 6:05 pm
Subject: automatic graphs in Excel; including other forecasts in sensitivity chart
jamesamurtha
Offline Offline
Send Email Send Email
 
Hello, All,

I have a model with a key forecast, Y, and 10 intermediate variables,
X1,...,X10, which I have designated as forecasts as well.

I want to automatically generate a two graphs in Excel ( they could be pictures
or charts):

a) a split view of Y as frequency, cumulative, statistics, and percentiles
b) a contribution to variance sensitivity chart  with target Y and ONLY the ten
forecasts X1,...X10 - no assumptions, like we could generate in previous
versions of Crystal Ball by "including" other forecasts.

Of course, one can do both of these things quickly off line:
a) having it the only graph to appear automatically, then migrating it to Excel
b) by extracting data and pasting it into a template where a the correlation
coefficients (rank if we want) are calculated and then normalized to get a live
bar chart.

As I look through the CB2000 developers' kit it looks like all this
functionality is (or was) possible. My questions are how much of the code is
still legitimate and has anyone got a better suggestion.
Regards,
Jim


web site: jmurtha.com

#2438 From: hils1978
Date: Thu Oct 29, 2009 3:33 pm
Subject: Re: automatic graphs in Excel; including other forecasts in sensitivity chart
hils1978
Offline Offline
 
Hi Jim,
All of this functionality is still available in the Developer's Kit.  You'll
want to refer to a newer copy of the documentation since there have been some
minor changes along the way.

1)  Automatically generating the forecast chart is shown in the Cost Estimating
example from the examples directory, but I've modified it slightly for the split
view.  See "Paste Chart.xls" in the files section.
2)  The cleverest approach I've seen to add forecasts in a sensitivity chart is
actually accomplished using the custom distribution.  You create dummy
assumptions corresponding to X1,...,X10 and the distribution references the
forecast for its only value.  There is an example titled "Sensitivity Analysis
Example.xls" that covers this technique in the files section.

Hope this is helpful.

Hilary

#2439 From: "jamesamurtha" <jmurtha@...>
Date: Thu Oct 29, 2009 8:57 pm
Subject: Re: automatic graphs in Excel; including other forecasts in sensitivity chart
jamesamurtha
Offline Offline
Send Email Send Email
 
Hi Hilary. It looks like the code for automatically pasting the forecast would
be only a few lines from that example, and I agree that the custom distribution
trick is a clever way to get non-assumptions into the sensitivity chart - kind
of the opposite of referencing an assumption to get an overlay.
I did find the latest Developer Kit among my files, so now I can be up to date.
Thanks for the quick and straightforward solutions.
Regards,
Jim


--- In cbug2@yahoogroups.com, hils1978 <no_reply@...> wrote:
>
>
> Hi Jim,
> All of this functionality is still available in the Developer's Kit.  You'll
want to refer to a newer copy of the documentation since there have been some
minor changes along the way.
>
> 1)  Automatically generating the forecast chart is shown in the Cost
Estimating example from the examples directory, but I've modified it slightly
for the split view.  See "Paste Chart.xls" in the files section.
> 2)  The cleverest approach I've seen to add forecasts in a sensitivity chart
is actually accomplished using the custom distribution.  You create dummy
assumptions corresponding to X1,...,X10 and the distribution references the
forecast for its only value.  There is an example titled "Sensitivity Analysis
Example.xls" that covers this technique in the files section.
>
> Hope this is helpful.
>
> Hilary
>

#2440 From: "eyunda" <eyunda@...>
Date: Wed Nov 4, 2009 5:09 am
Subject: Re: [CBUG] Conditional Value at Risk as criteria for Optimal Allocation
eyunda
Offline Offline
Send Email Send Email
 
Huybert:

I read your instructions and tried them but how to say to OptQuest that, what I
want is a CVaR efficient portfolio...

About your instructions:

1.- For your First Method: I applied:

Define Forecast > Forecast Window > Fit a probability distribution to the
forecast>

But, how to calculate the "integral" of the forecast distribution?
how to determine the left side of the percentile of interest? (it would require
other simulation... how to obtain it  "on the fly")
and then, how I can say to OptQuest: I want the CVaR efficient portfolio
defining the respective requirement to the objective function.


2. Your Second Method: "Extract all the values of the forecast distribution and
take the average of all the values on the left size of the percentile of
interest."

Are you suggesting to extract the values of the forecast distribution, for
example applying:

=CB.GetForeDataFN(U8;1)

many times (10000 times for 10000 trials)?.

How to do it automatically in Excel? Do you suggest "loops"? This means to write
Visual Basic code..  (really I would prefer only a Crystal Ball solution.. I
have not programmed VB yet.. though I learned C, Fortran and Quick Basic in the
University, you know).

Finally I would really appreciate if you could prepare an easy example (a
portfolio of assets) where Optquest delivers optimal portfolios and build a CVaR
efficient frontier.

On the other hand, let me insist that I would like a CB solution since I have
already obtained CVaR efficient frontiers using other software.  Consider that I
have rebuilded the same results for the CVaR.XLS example of Zenios' book
"Practical Financial Optimization" using GAMS, and also using  "What'sBest
10.0", and even applying Uryasev's "Portfolio Safeguard" student version. But, I
believe that Crystal Ball on the spreadsheet really is very useful and a
practical tool, that it is worth to spend a little more of time to achieve these
results, as many other people would appreciate this in due course.

Yours faithfully,

Edgar

--- In cbug2@yahoogroups.com, "Huybert Groenendaal" <huybert@...> wrote:
>
> Hi Edgar,
>
>
>
> Your question is an interesting and somewhat difficult one.
>
>
>
> For others on this list, CVaR, also known as `expected shortfall', basically
> is mean of all the returns of the portfolio within a certain timeframe and
> below (or above) a certain percentile. For example, the 1 year 1%-CVaR are
> the expected losses of a portfolio in a year period if the portfolio returns
> are below the 1% of the return distribution.
>
>
>
> In order to determine a portfolio in which you can use the CVaR to determine
> an efficient frontier with Crystal Ball, you would have to determine the
> CVaR of the portfolio each time OptQuest will come up with an alternative
> (and potentially better) asset allocation of your "n" stocks. The difficult
> part is to determine the CVaR "on the fly" for each new asset allocation.
> There are a number of ways of doing this, including:
>
> 1.       Fit a flexible distribution, ideally one that has a long tail, to
> the forecast distribution of your return and calculate the integral of the
> forecast distribution on the left side of the percentile of interest (in the
> above example, below the 1%-ile;
>
> 2.       Extract all the values of the forecast distribution and take the
> average of all the values on the left size of the percentile of interest.
>
> I'd expect with the use of VBA the second approach can be implemented in CB
> but I'd be interested to see if other members have alternative and maybe
> more efficient approaches. In any of the approaches, it will be important to
> run a lot of iterations since you are interested in the tails of the
> forecast distribution.
>
>
>
> Best wishes,
>
> Huybert
>
>
>
> From: cbug2@yahoogroups.com [mailto:cbug2@yahoogroups.com] On Behalf Of
> eyunda
> Sent: Monday, October 12, 2009 6:43 PM
> To: cbug2@yahoogroups.com
> Subject: [CBUG] Conditional Value at Risk as criteria for Optimal Allocation
>
>
>
>
>
> Please could you advise a Crystal Ball procedure for the following problem:
>
> Suppose that a portfolio contains "n" common stocks, and we are interested
> in recommend the optimal investment.
>
> But taking into account that this problem has to be solved now at least,
> with a coherent risk measure such as Conditional Value at Risk "CVaR" (it
> would be even better to apply more measures or risk functionals such as
> polyhedral risk measures as Eichhorn and Römisch of Humbolt Uni did)
>
> Then, what would be the Crystal Ball procedures to determine optimal
> portfolios (efficient frontier) by minimizing CVaR for a fixed return or by
> maximizing return for a given CVaR?
>
> Comments:
>
> Markowitz found optimal portfolios that could be located on an efficient
> frontier determined by minimizing variance when the return is fixed, or by
> maximizing return when the variance is given.
>
> Some year later, Value at Risk (VaR) appeared as Basilea requirement.
>
> However, neither mean-variance nor VaR are appropiate. In fact, Artzner and
> then Römisch and Pflug, indicated that mean-variance and VaR are not
> coherent risk measures, since diversification is not assured with them, even
> more when you have return distributions with fat tails.
>
> (I am preparing my Master Thesis about "Stochastic Optimization of
> Electricity Purchasing Contracts for Distribution Companies" in the National
> Polytechnic School of Quito, Ecuador, South America, with the help of the
> Math Department, and we are insisting that CB has to be useful to easily
> solve this problem inside Excel. But anyway, we are also working in GAMS
> (more difficult and programming codes) with CPLEX for MIP using scenario
> trees reduction to manage incertainty and we have certainly obtained the
> solution for this problem after some months of hard work)
>
> I would really appreciate your comments or even if you could prepare an
> example of efficient frontier for optimal portfolios determined with CVaR,
> in order to keep fighting until solving this problem, and then if we had a
> worked and clear example, we could share it to other interested in this
> subject.
>
> I am writing from my locally learned English, so please if you need more
> explanations, please do not hesitate in writing me. Anyway, eternally
> grateful.
>
> Yours faithfully,
>
> Edgar Yunda
> eyunda@... <mailto:eyunda%40yahoo.es>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

#2441 From: Steve Sacks <steves88@...>
Date: Fri Nov 6, 2009 1:11 am
Subject: Strange problem with Extreme Speed
steves88...
Offline Offline
Send Email Send Email
 
Hi,
 
      I hope somebody could give me some help with a really strange problem I am
having with Extreme Speed.  When I run a simulation at Normal Speed I get a
reasonable result.  When I then run the identical simulation at Extreme Speed, I
get the same result.  So far, so good.
 
       But, when I change one parameter and then run the simulation, again at
Extreme Speed, I get the same result as I got with the prior parameter; this is
not a reasonable result.  If I then re-run the simulation (with the changed
parameter) at Normal Speed, I get a different result, which is a reasonable
result (reasonably reflecting the changed parameter.)
 
      Since I have many parameters for which to run the simulation, it would
really be helpful to be able to do it at Extreme Speed instead of Normal Speed. 
To give this a quantitative measure, doing 1,000 trials at Normal Speed takes
about 10 minutes, while doing 1,000 trials at Extreme Speed takes less than 1
minute.  Since I have many dozen simulations to run, because of dozens of values
of various parameters, the time savings is really significant.
 
      Thanks in advance for any help anyone can provide.
 
                                    Steve Sacks

[Non-text portions of this message have been removed]

#2442 From: "blankind" <djb@...>
Date: Fri Nov 6, 2009 3:56 pm
Subject: Re: Strange problem with Extreme Speed
blankind
Offline Offline
Send Email Send Email
 
Steve,

The Extreme Speed engine uses a third party utility to speed up simulations (and
optimizations that run a series of simulations), but it does have a few
differences in behavior relative to Normal Speed of which you should be aware. 
I would recommend starting by reading the "Using the Extreme Speed Feature"
section in the Crystal Ball User's Guide.  One very useful tool for diagnosing
the nature of any numerical differences is the Compare Run Modes tool, which is
available under the More Tools menu alongside the other Crystal Ball tools.  The
Compare Run Modes tool runs Extreme Speed and Normal Speed simulations and
differences the results, pointing out which assumptions and/or forecasts have
different values when run in Extreme Speed rather than Normal Speed.  If you
still need assistance on the issue, such as having somebody review your model,
I'd recommend contacting Oracle Technical Support via the means listed at
http://www.oracle.com/crystalball.

David Blankinship
Manager, Quality Assurance
Crystal Ball Application
Oracle

--- In cbug2@yahoogroups.com, Steve Sacks <steves88@...> wrote:
>
> Hi,
>  
>       I hope somebody could give me some help with a really strange problem I
am having with Extreme Speed.  When I run a simulation at Normal Speed I get a
reasonable result.  When I then run the identical simulation at Extreme Speed, I
get the same result.  So far, so good.
>  
>        But, when I change one parameter and then run the simulation, again at
Extreme Speed, I get the same result as I got with the prior parameter; this is
not a reasonable result.  If I then re-run the simulation (with the changed
parameter) at Normal Speed, I get a different result, which is a reasonable
result (reasonably reflecting the changed parameter.)
>  
>       Since I have many parameters for which to run the simulation, it would
really be helpful to be able to do it at Extreme Speed instead of Normal Speed. 
To give this a quantitative measure, doing 1,000 trials at Normal Speed takes
about 10 minutes, while doing 1,000 trials at Extreme Speed takes less than 1
minute.  Since I have many dozen simulations to run, because of dozens of values
of various parameters, the time savings is really significant.
>  
>       Thanks in advance for any help anyone can provide.
>  
>                                     Steve Sacks
>
> [Non-text portions of this message have been removed]
>

#2443 From: Steve Sacks <steves88@...>
Date: Sat Nov 7, 2009 6:56 pm
Subject: Re: [CBUG] Re: Strange problem with Extreme Speed
steves88...
Offline Offline
Send Email Send Email
 
David,
 
        Thanks for your response to my question about Extreme Speed.
 
        In accordance with your suggestion, I did run the "Compare Run
Modes" tool for several different parameters in my model.  Unfortunately, the
results were extremely erratic -- sometimes the differences were very small and
other times the differences were substantial.  That is also true of running the
model itself in Extreme Speed and in Normal Speed.  Even more than I indicated
in my initial question, I find that in Extreme Speed I sometimes find really
aberrant results and sometimes only slightly aberrant results, and sometimes
reasonable results.  By contrast, in Normal Speed the results are always
reasonable.
 
       Therefore, I still need assistance, and I'd be very grateful to be
able to take advantage of your offer to "have somebody review my model."  I see
that you suggest I contact "www.oracle.com/crystalball."  Given that my model
deals with retirement planning and securities portfolios, could you provide a
more specifically focused contact?
 
          Thanks very much.
 
                                       
Steve Sacks

--- On Fri, 11/6/09, blankind <djb@...> wrote:


From: blankind <djb@...>
Subject: [CBUG] Re: Strange problem with Extreme Speed
To: cbug2@yahoogroups.com
Date: Friday, November 6, 2009, 3:56 PM


 



Steve,

The Extreme Speed engine uses a third party utility to speed up simulations (and
optimizations that run a series of simulations) , but it does have a few
differences in behavior relative to Normal Speed of which you should be aware. I
would recommend starting by reading the "Using the Extreme Speed Feature"
section in the Crystal Ball User's Guide. One very useful tool for diagnosing
the nature of any numerical differences is the Compare Run Modes tool, which is
available under the More Tools menu alongside the other Crystal Ball tools. The
Compare Run Modes tool runs Extreme Speed and Normal Speed simulations and
differences the results, pointing out which assumptions and/or forecasts have
different values when run in Extreme Speed rather than Normal Speed. If you
still need assistance on the issue, such as having somebody review your model,
I'd recommend contacting Oracle Technical Support via the means listed at
http://www.oracle. com/crystalball.

David Blankinship
Manager, Quality Assurance
Crystal Ball Application
Oracle

--- In cbug2@yahoogroups. com, Steve Sacks <steves88@.. .> wrote:
>
> Hi,
>  
>       I hope somebody could give me some help with a really strange
problem I am having with Extreme Speed.  When I run a simulation at Normal
Speed I get a reasonable result.  When I then run the identical simulation at
Extreme Speed, I get the same result.  So far, so good.
>  
>        But, when I change one parameter and then run the simulation,
again at Extreme Speed, I get the same result as I got with the prior parameter;
this is not a reasonable result.  If I then re-run the simulation (with the
changed parameter) at Normal Speed, I get a different result, which is a
reasonable result (reasonably reflecting the changed parameter.)
>  
>       Since I have many parameters for which to run the simulation, it
would really be helpful to be able to do it at Extreme Speed instead of Normal
Speed.  To give this a quantitative measure, doing 1,000 trials at Normal Speed
takes about 10 minutes, while doing 1,000 trials at Extreme Speed takes less
than 1 minute.  Since I have many dozen simulations to run, because of dozens
of values of various parameters, the time savings is really significant.
>  
>       Thanks in advance for any help anyone can provide.
>  
>                                     Steve
Sacks
>
> [Non-text portions of this message have been removed]
>








[Non-text portions of this message have been removed]

#2444 From: "Huybert Groenendaal" <huybert@...>
Date: Fri Nov 6, 2009 11:49 pm
Subject: RE: [CBUG] Conditional Value at Risk as criteria for Optimal Allocation
huybert
Offline Offline
Send Email Send Email
 
Hi Edgar,



Thank you for your email and updates.



In the previous email I outlined the general way (conceptually) how to go
about building a model for a CVar efficient portfolio.

To do this within CB without using VBA is however not very easy and I
currently don’t see how to do this.

Therefore, I hope that maybe others on the list have ideas/suggestions.



Best wishes,

Huybert



From: cbug2@yahoogroups.com [mailto:cbug2@yahoogroups.com] On Behalf Of
eyunda
Sent: Tuesday, November 03, 2009 10:09 PM
To: cbug2@yahoogroups.com
Subject: Re: [CBUG] Conditional Value at Risk as criteria for Optimal
Allocation





Huybert:

I read your instructions and tried them but how to say to OptQuest that,
what I want is a CVaR efficient portfolio...

About your instructions:

1.- For your First Method: I applied:

Define Forecast > Forecast Window > Fit a probability distribution to the
forecast>

But, how to calculate the "integral" of the forecast distribution?
how to determine the left side of the percentile of interest? (it would
require other simulation... how to obtain it "on the fly")
and then, how I can say to OptQuest: I want the CVaR efficient portfolio
defining the respective requirement to the objective function.

2. Your Second Method: "Extract all the values of the forecast distribution
and take the average of all the values on the left size of the percentile of
interest."

Are you suggesting to extract the values of the forecast distribution, for
example applying:

=CB.GetForeDataFN(U8;1)

many times (10000 times for 10000 trials)?.

How to do it automatically in Excel? Do you suggest "loops"? This means to
write Visual Basic code.. (really I would prefer only a Crystal Ball
solution.. I have not programmed VB yet.. though I learned C, Fortran and
Quick Basic in the University, you know).

Finally I would really appreciate if you could prepare an easy example (a
portfolio of assets) where Optquest delivers optimal portfolios and build a
CVaR efficient frontier.

On the other hand, let me insist that I would like a CB solution since I
have already obtained CVaR efficient frontiers using other software.
Consider that I have rebuilded the same results for the CVaR.XLS example of
Zenios' book "Practical Financial Optimization" using GAMS, and also using
"What'sBest 10.0", and even applying Uryasev's "Portfolio Safeguard" student
version. But, I believe that Crystal Ball on the spreadsheet really is very
useful and a practical tool, that it is worth to spend a little more of time
to achieve these results, as many other people would appreciate this in due
course.

Yours faithfully,

Edgar

--- In cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com> , "Huybert
Groenendaal" <huybert@...> wrote:
>
> Hi Edgar,
>
>
>
> Your question is an interesting and somewhat difficult one.
>
>
>
> For others on this list, CVaR, also known as `expected shortfall',
basically
> is mean of all the returns of the portfolio within a certain timeframe and
> below (or above) a certain percentile. For example, the 1 year 1%-CVaR are
> the expected losses of a portfolio in a year period if the portfolio
returns
> are below the 1% of the return distribution.
>
>
>
> In order to determine a portfolio in which you can use the CVaR to
determine
> an efficient frontier with Crystal Ball, you would have to determine the
> CVaR of the portfolio each time OptQuest will come up with an alternative
> (and potentially better) asset allocation of your "n" stocks. The
difficult
> part is to determine the CVaR "on the fly" for each new asset allocation.
> There are a number of ways of doing this, including:
>
> 1. Fit a flexible distribution, ideally one that has a long tail, to
> the forecast distribution of your return and calculate the integral of the
> forecast distribution on the left side of the percentile of interest (in
the
> above example, below the 1%-ile;
>
> 2. Extract all the values of the forecast distribution and take the
> average of all the values on the left size of the percentile of interest.
>
> I'd expect with the use of VBA the second approach can be implemented in
CB
> but I'd be interested to see if other members have alternative and maybe
> more efficient approaches. In any of the approaches, it will be important
to
> run a lot of iterations since you are interested in the tails of the
> forecast distribution.
>
>
>
> Best wishes,
>
> Huybert
>
>
>
> From: cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com>
[mailto:cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com> ] On Behalf
Of
> eyunda
> Sent: Monday, October 12, 2009 6:43 PM
> To: cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com>
> Subject: [CBUG] Conditional Value at Risk as criteria for Optimal
Allocation
>
>
>
>
>
> Please could you advise a Crystal Ball procedure for the following
problem:
>
> Suppose that a portfolio contains "n" common stocks, and we are interested
> in recommend the optimal investment.
>
> But taking into account that this problem has to be solved now at least,
> with a coherent risk measure such as Conditional Value at Risk "CVaR" (it
> would be even better to apply more measures or risk functionals such as
> polyhedral risk measures as Eichhorn and Römisch of Humbolt Uni did)
>
> Then, what would be the Crystal Ball procedures to determine optimal
> portfolios (efficient frontier) by minimizing CVaR for a fixed return or
by
> maximizing return for a given CVaR?
>
> Comments:
>
> Markowitz found optimal portfolios that could be located on an efficient
> frontier determined by minimizing variance when the return is fixed, or by
> maximizing return when the variance is given.
>
> Some year later, Value at Risk (VaR) appeared as Basilea requirement.
>
> However, neither mean-variance nor VaR are appropiate. In fact, Artzner
and
> then Römisch and Pflug, indicated that mean-variance and VaR are not
> coherent risk measures, since diversification is not assured with them,
even
> more when you have return distributions with fat tails.
>
> (I am preparing my Master Thesis about "Stochastic Optimization of
> Electricity Purchasing Contracts for Distribution Companies" in the
National
> Polytechnic School of Quito, Ecuador, South America, with the help of the
> Math Department, and we are insisting that CB has to be useful to easily
> solve this problem inside Excel. But anyway, we are also working in GAMS
> (more difficult and programming codes) with CPLEX for MIP using scenario
> trees reduction to manage incertainty and we have certainly obtained the
> solution for this problem after some months of hard work)
>
> I would really appreciate your comments or even if you could prepare an
> example of efficient frontier for optimal portfolios determined with CVaR,
> in order to keep fighting until solving this problem, and then if we had a
> worked and clear example, we could share it to other interested in this
> subject.
>
> I am writing from my locally learned English, so please if you need more
> explanations, please do not hesitate in writing me. Anyway, eternally
> grateful.
>
> Yours faithfully,
>
> Edgar Yunda
> eyunda@... <mailto:eyunda%40yahoo.es>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>





[Non-text portions of this message have been removed]

#2445 From: "Dave Winiarski" <david.winiarski@...>
Date: Mon Nov 9, 2009 10:19 pm
Subject: Use of volatile distributions and sequence of results using fixed seed value
Dave Winiarski
Offline Offline
Send Email Send Email
 
Is there some rule of thumb for how one should employ "volatile" custom
distributions?

I have a situation where the parameter range referred to in a custom
distribution is changing (the range of values used varies in terms of
values/probability as well as the number of values in the distribution).  Upon
opening the spreadsheet, the user creates the custom distribution on the fly.

We can't seem to get a repeatable string of results even using a fixed seed
value (999).  Looking at a small spreadsheet, example it looks like simply
redefining a custom distribution (going into the cell and hitting return)
commonly changes the results  almost as if in memory it put the newly defined
distribution somewhere else in the sequence of random values selected.  Simply
saving the spreadsheet and pulling it up again (where the macro redefines the
custom distribution with the same values), appears to result in a new sequence
of final CB results.

Any suggestions of a way to avoid this other than recoding the spreadsheet to
use "fixed" vs "volatile" custom distributions?

#2446 From: Samik Raychaudhuri <samikr@...>
Date: Tue Nov 10, 2009 5:00 am
Subject: Re: [CBUG] Use of volatile distributions and sequence of results using fixed seed value
samrcin
Offline Offline
Send Email Send Email
 
How are you defining your "volatile" custom distribution? Can you post a
small example?
-Samik

On 11/9/2009 3:19 PM, Dave Winiarski wrote:
>
> Is there some rule of thumb for how one should employ "volatile"
> custom distributions?
>
> I have a situation where the parameter range referred to in a custom
> distribution is changing (the range of values used varies in terms of
> values/probability as well as the number of values in the
> distribution). Upon opening the spreadsheet, the user creates the
> custom distribution on the fly.
>
> We can't seem to get a repeatable string of results even using a fixed
> seed value (999). Looking at a small spreadsheet, example it looks
> like simply redefining a custom distribution (going into the cell and
> hitting return) commonly changes the results almost as if in memory it
> put the newly defined distribution somewhere else in the sequence of
> random values selected. Simply saving the spreadsheet and pulling it
> up again (where the macro redefines the custom distribution with the
> same values), appears to result in a new sequence of final CB results.
>
> Any suggestions of a way to avoid this other than recoding the
> spreadsheet to use "fixed" vs "volatile" custom distributions?
>
>

#2448 From: "Dave Winiarski" <david.winiarski@...>
Date: Tue Nov 10, 2009 4:56 pm
Subject: Re: [CBUG] Use of volatile distributions and sequence of results using fixed seed value
Dave Winiarski
Offline Offline
Send Email Send Email
 
Posted an example.  (VolatileCustomDistributions.xls) I may be using the
terminology incorrectly.  Basically, what I noted was the order in which you
define the custom distributions in a CB spreadsheet seems to result in a
different set of values being selected for the forecast.  The problem was even
starting with the same seed value, we were getting different sequences of
results.  However we were using a macro to redefine the custom distributions to
point to different cells in one case, and back to the original distribution in
another case.  In going back and forth between the options, we were losing any
consistency in the series of values selected.

In the simple example I attached, which all point to the same distribution, you
can see that the sequence of results moves from one forecast to the other
forecast just dependent on which was last "created" (by going into the defined
assumption cell b4, c4, d4 and hitting enter)

This may simply be a known "feature" of how CB works internally.  However if so,
a workaround will be needed.

d

--- In cbug2@yahoogroups.com, Samik Raychaudhuri <samikr@...> wrote:
>
> How are you defining your "volatile" custom distribution? Can you post a
> small example?
> -Samik
>
> On 11/9/2009 3:19 PM, Dave Winiarski wrote:
> >
> > Is there some rule of thumb for how one should employ "volatile"
> > custom distributions?
> >
> > I have a situation where the parameter range referred to in a custom
> > distribution is changing (the range of values used varies in terms of
> > values/probability as well as the number of values in the
> > distribution). Upon opening the spreadsheet, the user creates the
> > custom distribution on the fly.
> >
> > We can't seem to get a repeatable string of results even using a fixed
> > seed value (999). Looking at a small spreadsheet, example it looks
> > like simply redefining a custom distribution (going into the cell and
> > hitting return) commonly changes the results almost as if in memory it
> > put the newly defined distribution somewhere else in the sequence of
> > random values selected. Simply saving the spreadsheet and pulling it
> > up again (where the macro redefines the custom distribution with the
> > same values), appears to result in a new sequence of final CB results.
> >
> > Any suggestions of a way to avoid this other than recoding the
> > spreadsheet to use "fixed" vs "volatile" custom distributions?
> >
> >
>

#2449 From: "Dave Winiarski" <david.winiarski@...>
Date: Tue Nov 10, 2009 6:07 pm
Subject: Re: [CBUG] Use of volatile distributions and sequence of results using fixed seed value
Dave Winiarski
Offline Offline
Send Email Send Email
 
Just to continue... the file that I posted shows three cells with a custom
distribution defined as an excel function in the testing tab, cells b4, c4, d4,
all pointing to the same data.
Forecasts cells reflecting this data is in b5, c5, d5.  In addition there is an
assumption cell d7 which also points to the same data.

The issue is that anytime you go into the cells b4, c4, or d4 and hit a return,
you effectively redefine the distribution I think.  This could also be done
using a macro.

You reset the simulation, which appears to reset the distribution sequence in
b4, c4, and d4 as well.  However when you run, the final sequence that you get
is dependent on which cell you last hit enter in.  Thus it appears like the
sequence for the distribution will change if you are just working with the
spreadsheet but not changing anything.  You can see this in the data tabs shown
with the workbook.

Ideally excel/CB would have figured out these distributions without regard to
the order in which the cells with the distributions were last accessed.

--- In cbug2@yahoogroups.com, "Dave Winiarski" <david.winiarski@...> wrote:
>
> Posted an example.  (VolatileCustomDistributions.xls) I may be using the
terminology incorrectly.  Basically, what I noted was the order in which you
define the custom distributions in a CB spreadsheet seems to result in a
different set of values being selected for the forecast.  The problem was even
starting with the same seed value, we were getting different sequences of
results.  However we were using a macro to redefine the custom distributions to
point to different cells in one case, and back to the original distribution in
another case.  In going back and forth between the options, we were losing any
consistency in the series of values selected.
>
> In the simple example I attached, which all point to the same distribution,
you can see that the sequence of results moves from one forecast to the other
forecast just dependent on which was last "created" (by going into the defined
assumption cell b4, c4, d4 and hitting enter)
>
> This may simply be a known "feature" of how CB works internally.  However if
so, a workaround will be needed.
>
> d
>
> --- In cbug2@yahoogroups.com, Samik Raychaudhuri <samikr@> wrote:
> >
> > How are you defining your "volatile" custom distribution? Can you post a
> > small example?
> > -Samik
> >
> > On 11/9/2009 3:19 PM, Dave Winiarski wrote:
> > >
> > > Is there some rule of thumb for how one should employ "volatile"
> > > custom distributions?
> > >
> > > I have a situation where the parameter range referred to in a custom
> > > distribution is changing (the range of values used varies in terms of
> > > values/probability as well as the number of values in the
> > > distribution). Upon opening the spreadsheet, the user creates the
> > > custom distribution on the fly.
> > >
> > > We can't seem to get a repeatable string of results even using a fixed
> > > seed value (999). Looking at a small spreadsheet, example it looks
> > > like simply redefining a custom distribution (going into the cell and
> > > hitting return) commonly changes the results almost as if in memory it
> > > put the newly defined distribution somewhere else in the sequence of
> > > random values selected. Simply saving the spreadsheet and pulling it
> > > up again (where the macro redefines the custom distribution with the
> > > same values), appears to result in a new sequence of final CB results.
> > >
> > > Any suggestions of a way to avoid this other than recoding the
> > > spreadsheet to use "fixed" vs "volatile" custom distributions?
> > >
> > >
> >
>

#2450 From: Wilfred Harper <wdrskh@...>
Date: Thu Nov 12, 2009 10:11 am
Subject: Using Crystal Ball in Decline Curve Analysis for estimating Oil and Gas reserves
wdrskh
Offline Offline
Send Email Send Email
 
I am using Crystal Ball 2000 standard edition v 5.2 to do decline curve
analysis. This requires applying a decline factor by month to an initial
production rate over the life time of a well which can be 20 to 25 years. I need
to develop the trend by months over the lifetime of the well and export the P10,
P50 and P90 data (by months) for charting in Excel. How can this be done
easily? I have attached a simple spreadsheet as an example.
 
Hope to get a solution.
Regards
wdrskh




[Non-text portions of this message have been removed]

#2451 From: Jim Marks <jim_marks@...>
Date: Thu Nov 12, 2009 6:57 pm
Subject: Crystal Ball 2000 in Excel 2007
james2002jamie
Offline Offline
Send Email Send Email
 
I am trying to run crystal ball 2000 in Excel 2007.



When I install, I get a type mismatch error from Visual Basic.



Has anyone encountered this? Does anyone know how to set up Crystal Ball in
Excel 2007?



thanks in advance



Jim

_________________________________________________________________
Eligible CDN College & University students can upgrade to Windows 7 before Jan 3
for only $39.99. Upgrade now!
http://go.microsoft.com/?linkid=9691819

[Non-text portions of this message have been removed]

#2452 From: "Pat Leach" <pat.leach@...>
Date: Fri Nov 13, 2009 12:39 am
Subject: RE: [CBUG] Using Crystal Ball in Decline Curve Analysis for estimating Oil and Gas reserves
leachpe
Offline Offline
Send Email Send Email
 
I don't believe CB 5.2 had the "auto-extract statistics" feature that we now
have, so the only way I know of to do this would be:



1)      Turn every month's production into a Forecast cell

2)      Let's assume your production forecasts run downward in your
spreadsheet row by row, and your first month is in cell A3.  In B3, put
"=CB.GetForePercentFN(A3,10)".  This will pull out the P10 value of the
forecast in A3.  Likewise, in columns C3 and D3, you put the same formula,
but the second arguments are 50 and 90, respectively, to pull out the P50
and P90.

3)      Copy these down for the life of your production.



These cells will show errors until you run CB, after which you will have a
string of  P10 values in column B, the P50s in column C, and the P90s in
column D.



But be careful what you do with this data.  These curves will reflect the
P10 - P90 range you can expect in any given month, but you do NOT have a
one-in-ten chance of achieving or exceeding the string of P90 values!  In
other words, you cannot play connect-the-dots with these data points and get
anything meaningful.  There is no such thing as a "P90 production profile".
You can derive a "typical production profile associated with the P90
cumulative production scenario," but that is a very different beast (and
trickier to get) than the simple string of P90 values you'll have here.



Does this make sense?



Pat Leach



From: cbug2@yahoogroups.com [mailto:cbug2@yahoogroups.com] On Behalf Of
Wilfred Harper
Sent: Thursday, November 12, 2009 4:12 AM
To: cbug2@yahoogroups.com
Subject: [CBUG] Using Crystal Ball in Decline Curve Analysis for estimating
Oil and Gas reserves





I am using Crystal Ball 2000 standard edition v 5.2 to do decline curve
analysis. This requires applying a decline factor by month to an initial
production rate over the life time of a well which can be 20 to 25 years. I
need to develop the trend by months over the lifetime of the well and export
the P10, P50 and P90 data (by months) for charting in Excel. How can this be
done easily? I have attached a simple spreadsheet as an example.

Hope to get a solution.
Regards
wdrskh

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

#2453 From: Andres Martingano <andres_martingano@...>
Date: Fri Nov 13, 2009 12:37 pm
Subject: RE: [CBUG] Using Crystal Ball in Decline Curve Analysis for estimating Oil and Gas reserves
andres_marti...
Offline Offline
Send Email Send Email
 
I agree with Pat.

I would use the CB Excel functions and be very careful on how I present the
results.

As
far as I know, there is no definition for 'percentile' for sets of
values that have to remain linked. By 'sets of values that have to
remain linked' I mean, e.g. each of the resulting production profiles
calculated for each trial, which should follow. As another possible
example (something I was looking at a couple of weeks ago) you can
consider the 'probabilistic IPRs'. I had a look at some results we
received and quickly built the example described in the attached
document to show that they were presented in a misleading way. I hope
that further illustrates Pat's point.

As a general rule I would
say: make sure all your calculations make physical / logical sense, and
don't report statistics of your results as if they represented a
physical / logical relationship.

Other than that, there's
still the question of ranking sets of values. My only asnwer to that is
define an indicator which reflects what you are looking for in your
sets of data. E.g. cumulative over the life of the well/field, average
rate for a certain period, time until a certain cumulative is
achieved... you name it.

I would be interested in hearing what
people are doing about this, and what people in other disciplines are
doing with similar problems.

Best regards,
Andres




[Non-text portions of this message have been removed]

#2454 From: "blankind" <djb@...>
Date: Fri Nov 13, 2009 2:41 pm
Subject: Re: Crystal Ball 2000 in Excel 2007
blankind
Offline Offline
Send Email Send Email
 
Jim,

Only Crystal Ball 7.3 and later are supported with Excel 2007.  You could run
into functional problems, including issues with the way that your Crystal Ball
data is stored in the Excel workbook, if you run with an older version of
Crystal Ball.

David Blankinship
Manager, Quality Assurance
Crystal Ball Application
Oracle

--- In cbug2@yahoogroups.com, Jim Marks <jim_marks@...> wrote:
>
>
> I am trying to run crystal ball 2000 in Excel 2007.
>
>
>
> When I install, I get a type mismatch error from Visual Basic.
>
>
>
> Has anyone encountered this? Does anyone know how to set up Crystal Ball in
Excel 2007?
>
>
>
> thanks in advance
>
>
>
> Jim
>
> _________________________________________________________________
> Eligible CDN College & University students can upgrade to Windows 7 before Jan
3 for only $39.99. Upgrade now!
> http://go.microsoft.com/?linkid=9691819
>
> [Non-text portions of this message have been removed]
>

#2455 From: Jim Marks <jim_marks@...>
Date: Fri Nov 13, 2009 8:54 pm
Subject: RE: [CBUG] Re: Crystal Ball 2000 in Excel 2007
james2002jamie
Offline Offline
Send Email Send Email
 
Thanks, David



To: cbug2@yahoogroups.com
From: djb@...
Date: Fri, 13 Nov 2009 14:41:06 +0000
Subject: [CBUG] Re: Crystal Ball 2000 in Excel 2007





Jim,

Only Crystal Ball 7.3 and later are supported with Excel 2007. You could run
into functional problems, including issues with the way that your Crystal Ball
data is stored in the Excel workbook, if you run with an older version of
Crystal Ball.

David Blankinship
Manager, Quality Assurance
Crystal Ball Application
Oracle

--- In cbug2@yahoogroups.com, Jim Marks <jim_marks@...> wrote:
>
>
> I am trying to run crystal ball 2000 in Excel 2007.
>
>
>
> When I install, I get a type mismatch error from Visual Basic.
>
>
>
> Has anyone encountered this? Does anyone know how to set up Crystal Ball in
Excel 2007?
>
>
>
> thanks in advance
>
>
>
> Jim
>
> __________________________________________________________
> Eligible CDN College & University students can upgrade to Windows 7 before Jan
3 for only $39.99. Upgrade now!
> http://go.microsoft.com/?linkid=9691819
>
> [Non-text portions of this message have been removed]
>





_________________________________________________________________
Windows Live: Friends get your Flickr, Yelp, and Digg updates when they e-mail
you.
http://go.microsoft.com/?linkid=9691817

[Non-text portions of this message have been removed]

#2456 From: Samik Raychaudhuri <samikr@...>
Date: Tue Nov 17, 2009 5:52 pm
Subject: Re: [CBUG] Use of volatile distributions and sequence of results using fixed seed value
samrcin
Offline Offline
Send Email Send Email
 
Hi Dave,
I understood the problem you are seeing. The reason is that, our excel
CB functions are not tied to the seed you specify in the run options.
The seed is only used if you are using CB assumptions. The excel
functions assume new seed every time. You can test that if you extract
the trial values for the assumption in the cell D7. For successive runs,
the trial values obtained from this assumption remains same (if the same
seed is used), but the trials obtained from Excel functions are different.
Thanks.
-Samik

On 11/10/2009 11:07 AM, Dave Winiarski wrote:
>
>
> Just to continue... the file that I posted shows three cells with a
> custom distribution defined as an excel function in the testing tab,
> cells b4, c4, d4, all pointing to the same data.
> Forecasts cells reflecting this data is in b5, c5, d5. In addition
> there is an assumption cell d7 which also points to the same data.
>
> The issue is that anytime you go into the cells b4, c4, or d4 and hit
> a return, you effectively redefine the distribution I think. This
> could also be done using a macro.
>
> You reset the simulation, which appears to reset the distribution
> sequence in b4, c4, and d4 as well. However when you run, the final
> sequence that you get is dependent on which cell you last hit enter
> in. Thus it appears like the sequence for the distribution will change
> if you are just working with the spreadsheet but not changing
> anything. You can see this in the data tabs shown with the workbook.
>
> Ideally excel/CB would have figured out these distributions without
> regard to the order in which the cells with the distributions were
> last accessed.
>
> --- In cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com>, "Dave
> Winiarski" <david.winiarski@...> wrote:
> >
> > Posted an example. (VolatileCustomDistributions.xls) I may be using
> the terminology incorrectly. Basically, what I noted was the order in
> which you define the custom distributions in a CB spreadsheet seems to
> result in a different set of values being selected for the forecast.
> The problem was even starting with the same seed value, we were
> getting different sequences of results. However we were using a macro
> to redefine the custom distributions to point to different cells in
> one case, and back to the original distribution in another case. In
> going back and forth between the options, we were losing any
> consistency in the series of values selected.
> >
> > In the simple example I attached, which all point to the same
> distribution, you can see that the sequence of results moves from one
> forecast to the other forecast just dependent on which was last
> "created" (by going into the defined assumption cell b4, c4, d4 and
> hitting enter)
> >
> > This may simply be a known "feature" of how CB works internally.
> However if so, a workaround will be needed.
> >
> > d
> >
> > --- In cbug2@yahoogroups.com <mailto:cbug2%40yahoogroups.com>, Samik
> Raychaudhuri <samikr@> wrote:
> > >
> > > How are you defining your "volatile" custom distribution? Can you
> post a
> > > small example?
> > > -Samik
> > >
> > > On 11/9/2009 3:19 PM, Dave Winiarski wrote:
> > > >
> > > > Is there some rule of thumb for how one should employ "volatile"
> > > > custom distributions?
> > > >
> > > > I have a situation where the parameter range referred to in a
> custom
> > > > distribution is changing (the range of values used varies in
> terms of
> > > > values/probability as well as the number of values in the
> > > > distribution). Upon opening the spreadsheet, the user creates the
> > > > custom distribution on the fly.
> > > >
> > > > We can't seem to get a repeatable string of results even using a
> fixed
> > > > seed value (999). Looking at a small spreadsheet, example it looks
> > > > like simply redefining a custom distribution (going into the
> cell and
> > > > hitting return) commonly changes the results almost as if in
> memory it
> > > > put the newly defined distribution somewhere else in the
> sequence of
> > > > random values selected. Simply saving the spreadsheet and
> pulling it
> > > > up again (where the macro redefines the custom distribution with
> the
> > > > same values), appears to result in a new sequence of final CB
> results.
> > > >
> > > > Any suggestions of a way to avoid this other than recoding the
> > > > spreadsheet to use "fixed" vs "volatile" custom distributions?
> > > >
> > > >
> > >
> >
>
>

#2457 From: "davidjromano" <david.j.romano@...>
Date: Mon Nov 23, 2009 3:53 pm
Subject: Can anyone help me get CB to run on the new Microft technology
davidjromano
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Hi,

I've just upgraded my computer to Win 7 Ultimate x64 with Office 2010 x64 (beta)
on a Sun Ultra 40 M2 with 20Gb of RAM (.NET 3.5 appears to be native to Win 7
and I also have .NET 4.2 (beta) installed - filename dotNetFx40_Full_x86_x64).

Has anyone tried, or better still, succeeded in getting CB to run under Win 7
with Excel 2010 x64? (It seems fine under Win 7 with Excel 2007 (x32) and I
havent tried Excel 2010 x86).

Any help would be appreciated, thanks, david

#2458 From: "Bill Rapp" <Bill@...>
Date: Wed Nov 25, 2009 2:29 am
Subject: Crystal Ball Performance with new Quad Core Processors
rawj53
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Hello,

I am contemplating the specifications of a new laptop computer which is on
my "to buy" list.

Does anyone have any experience with running Crystal Ball on the new ""Quad
Core" processors now being offered either with or without a Windows 64 bit
operating system.

I am particularly interested to see whether these new processors offer a
significant  increase in computing speed when running large CB models with
Excel.

Looking forward to your responses.

Thanks,

Bill Rapp



[Non-text portions of this message have been removed]

#2459 From: "David.J.Romano" <david.j.romano@...>
Date: Wed Nov 25, 2009 9:37 am
Subject: FW: Crystal Ball Performance with new Quad Core Processors
davidjromano
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Bill,



This isn't a direct answer to your question but might be of relevance.



I'm running off a Sun Ultra40 M2 multi-processor/multi-core machine with
20Gb Ram  under Win7 x64 with Excel 2010 x64 (beta) and the performance of
Excel x64 is stunning compared with the x86 version: It now runs appreciably
faster than even SAS JMP which I also use.



Presently I've had to stop using CB because it doesn't support Win7 x64
(does run though) and can't support Excel x64 but there seems every reason
to suppose that CB will gain a similar performance increment under x64
whenever it gets released in x64 form.



(In case anyone asks, I have tried installing theCB x86 image but though it
does run under Win7 x64 - but with page faults on termination - it will not
run under Excel x64 though the installation reports that it has installed
correctly.)



Best regards,

David



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#2460 From: "JEFF" <rocdoc76051@...>
Date: Wed Nov 25, 2009 2:24 pm
Subject: obnoxous notice screen when saving file
rocdoc76051
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Hi - I am building some low-end models that contain formulae that I want to
protect and keep hidden.  the models are run with VBA that unprotects the
sheets, runs CB, extracts the results and then reprotects the sheets.

With CB7/11 I get an obnoxious notice when I attempt to save the file, telling
me to consider unprotecting the sheets before saving.  When I click OK it seems
to save fine.

Is there any way to suppress this notice screen?  This did not happen with older
versions of CB

thanks-
Jeff in Tennessee (hi, Pat and Bill)

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