.- help for ^nptr^ (manual: [5s] trend) .- Nonparametric test for trend across ordered groups -------------------------------------------------- ^nptrend^ varname [^if^ exp] [^in^ range]^, b^y^(^groupvar^)^ [^nod^etail ^s^core^(^scorevar^)^] Description ----------- ^nptrend^ performs a nonparametric test for trend across ordered groups. This test, developed by Cuzick (1985), is an extension of the Wilcoxon rank-sum test and is a useful adjunct to the Kruskal-Wallis test (see help @kwallis@). The formula for the test statistic is given by Cuzick(1985) and Altman(1991). The formula incorporates a correction for ties. When no options are specified, the values of ^groupvar^ are used for the scores. Options ------- ^b^y^(^groupvar^)^ is not optional; it defines groups. ^nod^etail suppresses the listing of group rank sums. The default is to display this listing. ^ordinal^ uses the values 1, 2,3 $\ldots$ instead of the values in as the scores in the test. ^midrank^ uses the midranks of instead of the values in as the scores in the test. This is equivalent to ridit scores. Note that ^midrank^ is an alternative to ^ordinal^. When no ^scorevar^ is specified, the values of ^groupvar^ are used for the scores. Example ------- . ^nptrend exposure, by(group)^ group score obs sum of ranks 1 1 6 76 2 2 18 290 3 3 8 162 z = 1.52, chi-squared(1) = 2.31 P>|z| = 0.1286 Also see -------- Manual: [5s] trend On-line: help for @runtest@