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Oracle® Database SQL Reference
10g Release 1 (10.1)

Part Number B10759-01
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Description of stats_wsr_test.gif follows
Description of the illustration stats_wsr_test.gif


STATS_WSR_TEST is a Wilcoxon Signed Ranks test of paired samples to determine whether the median of the differences between the samples is significantly different from zero. The absolute values of the differences are ordered and assigned ranks. Then the null hypothesis states that the sum of the ranks of the positive differences is equal to the sum of the ranks of the negative differences.

This function takes three arguments: expr1 and expr2 are the two samples being analyzed, and the third argument is a return value of type VARCHAR2. If you omit the third argument, the default is TWO_SIDED_SIG. The meaning of the return values is shown in Table 7-10.

Table 7-10 STATS_WSR_TEST_* Return Values

Return Value Meaning
STATISTIC The observed value of Z
ONE_SIDED_SIG One-tailed significance of Z
TWO_SIDED_SIG Two-tailed significance of Z