Create a Random Sample - Options Tab

Select the Options tab of the Create a Random Sample dialog box to access the options described below.

Use case selection condition expression. If this check box is selected, the case selection conditions specified via the Cases button will be applied before any further sampling is performed; clear this check box to ignore any case selection conditions.

Copy formatting to new spreadsheet cases. Select this check box to retain the cell format(s) of the original cases in the new subset(s).

Options for random sampling. The options in this group box pertain to simple random sampling, stratified random sampling, and random splitting of the data file only (see also the Simple Sampling and Stratified Sampling tabs).

Use Diehard-certified random number generator (note: this algorithm is slower). Statistica uses a very carefully designed and tested random number generator (see DIEHARD Suite of Tests and Random Number Generation) whenever random numbers are required for certain operations or procedures (and this default highest-quality random number generator can be used for even the most demanding modeling and simulation projects and Monte Carlo experiments). However, for most simple random or stratified random sampling, simpler and faster methods for randomly selecting the cases (observations) for the final sample can be used. In particular for very large data sets and samples, clear this check box (to use the simpler random number generator) to draw samples more efficiently.

Calculate based on percentage of cases. Select this option button to specify the sampling fraction(s) for simple random or stratified sampling, or for splitting the data file, in terms of percentages.

Calculate based on count of cases. Select this option button to specify the sampling fractions for simple random or stratified sampling, or for splitting the data file, in terms of the approximate number of cases in the final sample (or strata). Note that if sample sizes (Approximate N) are requested that are greater than the actual number of cases belonging to the respective strata in the population (in the input file), then all cases from those strata will be selected into the final sample.