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Sample size
Sample size
The sample size option is located on the Run Preferences > Sampling dialog
(page 83). Sample size, which is initially set to 500, affects Latin hypercube
sampling. It divides each assumption’s distribution into a number of intervals
of equal probability. The sample size governs the number of intervals for each
distribution. Crystal Ball generates an assumption value for each interval
according to the interval’s probability distribution.
While any sample size greater than 100 should produce sufficiently acceptable
results, you can set this number higher to maximize accuracy. There is no
absolute limit to sample size, although samples greater than 100,000 work
best with at least 1 GB RAM and might take a long time to run. The increased
accuracy resulting from the use of larger samples, however, requires
additional memory. If memory becomes an issue, reduce the sample size and
consider adding more RAM.
Correlated assumptions
There is a practical limit of about 250 fully correlated assumptions
(assumptions that are correlated to every other assumption) and up to about
1,000 serially correlated assumptions (assumptions that are correlated to one
or two other assumptions) for each workbook. If you have a large number of
correlated assumptions:
• For coefficients that are close to zero and are nearly independent, remove
the correlation.
• For coefficients that are close to one, replace one of the assumptions with
a formula in your spreadsheet.
If Crystal Ball detects inconsistently correlated assumptions when a
simulation is running, it first determines whether small adjustments to the
correlation coefficients are possible. This process might take a long time,
depending on the number of correlated assumptions. Crystal Ball displays the
message “Examining the Correlation Coefficients”. If you get this message,
you should probably stop and redefine your correlations.
If small adjustments to the correlation coefficients are possible, a dialog
appears, letting you decide whether to cancel the simulation or continue with
the adjusted coefficients.
Select one of the following responses:
Crystal Ball User Manual
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