User Guide

194
Chapter 8
Figure 8-11
Select Cases Random Sample dialog box
Approximately. Generates a random sample of approximately the specified percentage
of cases. Since this routine makes an independent pseudo-random decision for each
case, the percentage of cases selected can only approximate the specified percentage.
The more cases there are in the data file, the closer the percentage of cases selected
is to the specified percentage.
Exactly. A user-specified number of cases. You must also specify the number of
cases from which to generate the sample. This second number should be less than
or equal to the total number of cases in the data file. If the number exceeds the
total number of cases in the data file, the sample will contain proportionally fewer
cases than the requested number.
Select Cases: Range
This dialog box selects cases based on a range of case numbers or a range of dates
or times.
 Case ranges are based on row number as displayed in the Data Editor.
 Date and time ranges are available only for time series data with defined date
variables (Data menu, Define Dates).