PERCENTILES Subcommand (EXAMINE command)
PERCENTILES displays the Percentiles table. If PERCENTILES is omitted, no percentiles are produced. If PERCENTILES is specified without keywords, HAVERAGE is used with default break points
of 5, 10, 25, 50, 75, 90, and 95.
- Values for break points are specified in parentheses
following the subcommand.
EXAMINEdisplays up to six decimal places for user-specified percentile values. - The method keywords follow the specifications for break points.
For each of the following methods of percentile calculation, w is the sum of the weights for all nonmissing cases, p is the specified percentile divided by 100, and X i is the value of the ith case (cases are assumed to be ranked in ascending order). For details on the specific formulas used, see the algorithms documentation included on the installation CD.
HAVERAGE. Weighted average at X(w + 1)p. The percentile value is the
weighted average of X i and X i + 1, where i is the integer part of (w + 1)p. This is the default if PERCENTILES is specified without a keyword.
WAVERAGE. Weighted average at Xwp. The percentile value is the weighted average of X i and X (i + 1), where i is the integer portion of wp.
ROUND. Observation closest to wp. The percentile value is X i or X i + 1, depending upon whether i or i + 1 is "closer" to wp.
EMPIRICAL. Empirical distribution function. The percentile value is X i, where i is equal to wp rounded up to the next integer.
AEMPIRICAL. Empirical distribution
with averaging. This is equivalent to EMPIRICAL, except when i=wp, in which case the percentile value
is the average of X i and X i + 1.
NONE. Suppress percentile
output. This is the default if PERCENTILES is omitted.
Example
EXAMINE VARIABLE=SALARY /PERCENTILES(10,50,90)=EMPIRICAL.-
PERCENTILESproduces the 10th, 50th, and 90th percentiles for the dependent variable SALARY using theEMPIRICALdistribution function.