size.test.gen2

Computes the sample size per group required to test a difference in two
populatation parameters with desired power using a standard error for a
single parameter estimate from a prior or pilot study. This function can be
used with any type of parameter where the standard error of the parameter
estimate is a function of the square root of the sample size (most parameter
estimates have this property). This function also assumes that the sampling
distribution of the parameter estimate is approximately normal in large
samples. Set R = 1 for equal sample sizes.

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

size.test.gen2 function

<dl><dt>alpha</dt>
<dd>alpha level for hypothesis test</dd>
<dt>pow</dt>
<dd>desired power</dd>
<dt>se</dt>
<dd>standard error of parameter estimate from prior/pilot study</dd>
<dt>n0</dt>
<dd>sample size of prior/pilot study</dd>
<dt>es</dt>
<dd>planning value of parameter difference</dd>
<dt>R</dt>
<dd>n2/n1 ratio</dd></dl>

Arguments

Sample size for a test of 2-group difference for any type of parameter — size.test.gen2

<dl>

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


<dt>pow</dt>
<dd>desired power</dd>


<dt>se</dt>
<dd>standard error of parameter estimate from prior/pilot study</dd>


<dt>n0</dt>
<dd>sample size of prior/pilot study</dd>


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


<dt>R</dt>
<dd>n2/n1 ratio</dd>

</dl>

size.test.gen2: Sample size for a test of 2-group difference for any type of parameter

Description

Usage

Value

Arguments

Examples