pi.var.upper

Computes an upper prediction limit for the estimated variance in a
future study for a planned sample size. The prediction limit uses a
variance estimate from a prior study. Several confidence interval
sample size functions in this package require a planning value of the
estimated variance that is expected in the planned study. The upper variance
prediction limit is useful as a variance planning value for the sample size
required to obtain a confidence interval with desired width. This strategy
for specifying a variance planning value is useful in applications where the
population variance in the prior study is assumed to be very similar to the
population variance in the planned study. This function will be replaced with
pi.var which computes both one-sided and two-sided prediction limits.

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.var.upper function

<dl><dt>alpha</dt>
<dd>alpha value for upper 1-alpha confidence</dd>
<dt>var</dt>
<dd>estimated variance from prior study</dd>
<dt>n0</dt>
<dd>sample size used to estimate variance</dd>
<dt>n</dt>
<dd>planned sample size of future study</dd></dl>

Arguments

Upper prediction limit for an estimated variance — pi.var.upper

<dl>

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


<dt>var</dt>
<dd>estimated variance from prior study</dd>


<dt>n0</dt>
<dd>sample size used to estimate variance</dd>


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

</dl>

pi.var.upper: Upper prediction limit for an estimated variance

Description

Usage

Value

Arguments

References

Examples