power.mann

Computes the approximate power of a Mann-Whitney U test for a planned
sample size. In a 2-group experiment, the effect size is the proportion
of members in the population with scores that would be higher under
treatment 1 than treatment 2. In a 2-group nonexperiment where participants
are sampled from two subpopulations of sizes N1 and N2, the effect size is
the proportion of all N1 x N2 pairs in which a member from subpopulation 1
has a larger score than a member from subpopulation 2.

Implements confidence interval and sample size methods that are especially
useful in psychological research but are also useful in educational, social science,
business, and biological research. This package includes more than 100 confidence
interval functions and more than 80 sample size functions for 1-group, 2-group,
paired-samples, and multiple-group designs and for a variety of parameters including
means, medians, proportions, slopes, standardized mean differences, standardized
linear contrasts of means, and several measures of correlation and association. The
sample size functions can be used to approximate the sample size needed to estimate
a parameter or function of parameters with desired confidence interval precision or
to perform a variety of hypothesis tests (directional two-sided, equivalence,
superiority, noninferiority) with desired power. For details about these methods see:
Statistical Methods for Psychologists, Volumes 1 – 4, <https://dgbonett.sites.ucsc.edu/>.

Douglas G. Bonett

statpsych

Statistical Methods for Psychologists

Robert J. Calin-Jageman

power.mann function

<dl><dt>alpha</dt>
<dd>alpha level for hypothesis test</dd>
<dt>n1</dt>
<dd>planned sample size for group 1</dd>
<dt>n2</dt>
<dd>planned sample size for group 2</dd>
<dt>es</dt>
<dd>planning value of effect size (between .5 and 1)</dd></dl>

Arguments

Approximates the power of a Mann-Whitney test — power.mann

<dl>

<dt>alpha</dt>
<dd>alpha level for hypothesis test</dd>


<dt>n1</dt>
<dd>planned sample size for group 1</dd>


<dt>n2</dt>
<dd>planned sample size for group 2</dd>


<dt>es</dt>
<dd>planning value of effect size (between .5 and 1)</dd>

</dl>

power.mann: Approximates the power of a Mann-Whitney test

Description

Usage

Value

Arguments

References

Examples