SPSS® 12.0 Command Syntax Reference

SAMPLE 1447
• If SAMPLE precedes SELECT IF, cases are selected from the sample.
• If more than one SAMPLE is specified in a session, each acts upon the sample selected by
the preceding SAMPLE command.
• If N OF CASES is used with SAMPLE, the program reads as many records as required to
build the specified n cases. It makes no difference whether the N OF CASES precedes or
follows the SAMPLE.
Limitations
Example
Example
Example
SAMPLE cannot be placed in a FILE TYPE—END FILE TYPE or INPUT PROGRAM—END INPUT
PROGRAM structure. It can be placed nearly anywhere following these commands in a transformation
program. See Appendix A for a discussion of program states and the placement of
commands.
SAMPLE .25.
• This command samples approximately 25% of the cases in the working data file.
SAMPLE 500 FROM 3420.
• The working data file must have 3420 cases or more to obtain a random sample of exactly
500 cases.
• If the file contains fewer than 3420 cases, proportionally fewer cases are sampled.
• If the file contains more than 3420 cases, a random sample of 500 cases is drawn from the
first 3420 cases.
DO IF SEX EQ ’M’.
SAMPLE 1846 FROM 8000.
END IF.
• SAMPLE is placed inside a DO IF—END IF structure to sample subgroups differently.
Assume that this is a survey of 10,000 people in which 80% of the sample is male, while
the known universe is 48% male. To obtain a sample that corresponds to the known
universe and that maximizes the size of the sample, 1846 (48/52*2000) males and all
females must be sampled. The DO IF structure is used to restrict the sampling process to
the males.