ci.cqv

Computes a distribution-free confidence interval for a population coefficient
of quartile variation which is defined as (Q3 - Q1)/(Q3 + Q1) where Q1 is the
25th percentile and Q3 is the 75th percentile. The coefficient of quartile
variation assumes ratio-scale scores and is a robust alternative to the
coefficient of variation. The 25th and 75th percentiles are computed using
the type = 2 method (SAS default).

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

ci.cqv function

<dl><dt>alpha</dt>
<dd>alpha level for 1-alpha confidence</dd>
<dt>y</dt>
<dd>vector of scores</dd></dl>

Arguments

Confidence interval for a coefficient of quartile variation — ci.cqv

<dl>

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


<dt>y</dt>
<dd>vector of scores</dd>

</dl>

ci.cqv: Confidence interval for a coefficient of quartile variation

Description

Usage

Value

Arguments

References

Examples