size.ci.second

Computes the second-stage sample size required to obtain desired confidence
interval precision. This function can use either the total sample size for
all groups in the first stage sample or a single group sample size in the
first stage sample. If the total first-stage sample size is given, then the
function computes the total sample size required in the second-stage sample.
If a single group first-stage sample size is given, then the function
computes the single-group sample size required in the second-stage sample.
The second-stage sample is combined with the first-stage sample to obtain
the desired confidence interval width.

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.ci.second function

<dl><dt>n0</dt>
<dd>first-stage sample size</dd>
<dt>w0</dt>
<dd>confidence interval width in first-stage sample</dd>
<dt>w</dt>
<dd>desired confidence interval width</dd></dl>

Arguments

Sample size for a second-stage confidence interval — size.ci.second

<dl>

<dt>n0</dt>
<dd>first-stage sample size</dd>


<dt>w0</dt>
<dd>confidence interval width in first-stage sample</dd>


<dt>w</dt>
<dd>desired confidence interval width</dd>

</dl>

size.ci.second: Sample size for a second-stage confidence interval

Description

Usage

Value

Arguments

Examples