power.mean2

Computes the approximate power of a two-sample t-test for planned sample
sizes. For a conservatively low power approximation, set the variance
planning values to the largest values within their plausible ranges,
and set the effect size to a minimally interesting value. The within-group
variances can be unequal across groups and a Satterthwaite degree of freedom
adjustment is used to improve the accuracy of the power approximation.

Implements confidence interval and sample size methods that
are especially useful in psychological research. The methods can be
applied in 1-group, 2-group, paired-samples, and multiple-group designs
and to a variety of parameters including means, medians, proportions,
slopes, standardized mean differences, standardized linear contrasts
of means, plus several measures of correlation and association.
Confidence interval and sample size functions are given for single
parameters as well as differences, ratios, and linear contrasts of
parameters. 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 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.mean2 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>var1</dt>
<dd>planning value of within-group variance for group 1</dd>
<dt>var2</dt>
<dd>planning value of within-group variance for group 2</dd>
<dt>es</dt>
<dd>planning value of mean difference</dd></dl>

Arguments

Approximates the power of a two-sample t-test for planned sample sizes — power.mean2

<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>var1</dt>
<dd>planning value of within-group variance for group 1</dd>


<dt>var2</dt>
<dd>planning value of within-group variance for group 2</dd>


<dt>es</dt>
<dd>planning value of mean difference</dd>

</dl>

power.mean2: Approximates the power of a two-sample t-test for planned sample sizes

Description

Usage

Value

Arguments

Examples