SAMPLE num1 [FROM num2].
SAMPLE randomly samples a proportion of the cases in the active
file. Unless it follows
TEMPORARY, it operates as a
transformation, permanently removing cases from the active dataset.
The proportion to sample can be expressed as a single number between 0
and 1. If k is the number specified, and N is the number
of currently-selected cases in the active dataset, then after
SAMPLE k., approximately k*N cases are
The proportion to sample can also be specified in the style
m FROM N. With this style, cases are selected as follows:
SELECT IF are performed in
the order specified by the syntax file.
SAMPLE is always performed before
N OF CASES, regardless
of ordering in the syntax file (see N OF CASES).
The same values for
SAMPLE may result in different samples. To
obtain the same sample, use the
SET command to set the random
number seed to the same value before each
samples may still result when the file is processed on systems with
differing endianness or floating-point formats. By default, the
random number seed is based on the system time.