pi.cor

Computes approximate one-sided or two-sided prediction limits for the
estimated Pearson correlation in a future study with a planned sample
size of n. The prediction interval uses a correlation estimate from a
prior study that had a sample size of n0.
Several confidence interval sample size functions in this package require
a planning value of the estimated Pearson correlation that is expected
in the planned study. A one-sided lower correlation prediction limit is
useful as a correlation planning value for the sample size required to
obtain a confidence interval with desired width. This strategy for
specifying a correlation planning value is useful in applications where
the population correlation in the prior study is assumed to be very similar
to the population correlation in the planned study.

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

pi.cor function

<dl><dt>alpha</dt>
<dd>alpha value for 1-alpha confidence</dd>
<dt>cor</dt>
<dd>estimated Pearson correlation from prior study</dd>
<dt>n0</dt>
<dd>sample size used to estimate correlation in prior study</dd>
<dt>n</dt>
<dd>planned sample size of future study</dd>
<dt>type</dt>
<dd><ul>
<li>set to 1 for two-sided prediction interval</li>
<li>set to 2 for one-sided upper prediction limit</li>
<li>set to 3 for one-sided lower prediction limit</li>
</ul></dd></dl>

Arguments

Prediction limits for an estimated correlation — pi.cor

<dl>

<dt>alpha</dt>
<dd>alpha value for 1-alpha confidence</dd>


<dt>cor</dt>
<dd>estimated Pearson correlation from prior study</dd>


<dt>n0</dt>
<dd>sample size used to estimate correlation in prior study</dd>


<dt>n</dt>
<dd>planned sample size of future study</dd>


<dt>type</dt>
<dd><ul>
<li>set to 1 for two-sided prediction interval</li>
<li>set to 2 for one-sided upper prediction limit</li>
<li>set to 3 for one-sided lower prediction limit</li>
</ul></dd>

</dl>

pi.cor: Prediction limits for an estimated correlation

Description

Usage

Value

Arguments

Examples