N [OF CASES] num_of_cases [ESTIMATED].
N OF CASES limits the number of cases processed by any
procedures that follow it in the command stream. N OF CASES
100, for example, tells PSPP to disregard all cases after the first
100.
When N OF CASES is specified after TEMPORARY, it affects
only the next procedure (see TEMPORARY). Otherwise, cases beyond
the limit specified are not processed by any later procedure.
If the limit specified on N OF CASES is greater than the number
of cases in the active dataset, it has no effect.
When N OF CASES is used along with SAMPLE or SELECT
IF, the case limit is applied to the cases obtained after sampling or
case selection, regardless of how N OF CASES is placed relative
to SAMPLE or SELECT IF in the command file. Thus, the
commands N OF CASES 100 and SAMPLE .5 both randomly
sample approximately half of the active dataset’s cases, then select the
first 100 of those sampled, regardless of their order in the command
file.
N OF CASES with the ESTIMATED keyword gives an estimated
number of cases before DATA LIST or another command to read in
data. ESTIMATED never limits the number of cases processed by
procedures. PSPP currently does not make use of case count estimates.