ci.sd

Computes the traditional confidence interval for a population standard
deviation using a sample estimate of the standard deviation. The traditional
confidence interval assumes normality and is hypersensitive to minor
violations of this assumption. This function should be used only if the
data appear to come from an approximate normal or mildly platykurtic
distribution.

Implements confidence interval and sample size methods that are especially
useful in psychological research but are also useful in educational, social science,
business, and biological research. This package includes more than 100 confidence
interval functions and more than 80 sample size functions for 1-group, 2-group,
paired-samples, and multiple-group designs and for a variety of parameters including
means, medians, proportions, slopes, standardized mean differences, standardized
linear contrasts of means, and several measures of correlation and association. 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 about these methods 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

ci.sd function

<dl><dt>alpha</dt>
<dd>alpha value for 1-alpha confidence</dd>
<dt>sd</dt>
<dd>estimated standard deviation</dd>
<dt>n</dt>
<dd>sample size</dd></dl>

Arguments

Confidence interval for a standard deviation — ci.sd

<dl>

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


<dt>sd</dt>
<dd>estimated standard deviation</dd>


<dt>n</dt>
<dd>sample size</dd>

</dl>

ci.sd: Confidence interval for a standard deviation

Description

Usage

Value

Arguments

Examples