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help for ^kwallis2^
by Herve M. CACI, May 1999
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One-way analysis of variance by ranks (Kruskal-Wallis Test)
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^kwallis2^ varname [^if^ exp] [^in^ range]^, by(^groupvar^) control(^#^)
Description
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^kwallis2^ is an extremely useful test for deciding whether k indepedent
samples are from different populations. The null hypothesis is that k samples
come from the same population or from identical populations with the same
median. When a significant value is found, ^kwallis2^ determine which groups are
different.
varname refers to the variable recording the outcome and groupvar refers to the
variable denoting the population. Note that the ^by()^ "option" is not optional.
With the ^control()^ option, you may specify which group is to be considered as
a control group or a standard group. For example, when a researcher wishes to
assess the effects of various drugs on behavior.
Example
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. ^kwallis2 medage, by(region)^
. ^kwallis2 behavior, by(drug) control(1)^
Also see
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Manual: ^[R] kwallis^
On-line: help for @nptrend@, @oneway@, @runtest@, @signrank@
Book: Siegel S. & Castellan J.
"Nonparametric Statistics for the Behavioral Sciences"
Chap. 8 (1988) McGraw-Hill