sim.ci.median2

Performs a computer simulation of the confidence interval performance for a
difference of population medians in a 2-group design. Sample data for each
group can be generated from five different population distributions. All
distributions are scaled to have standard deviations of 1.0 in group 1.

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

sim.ci.median2 function

<dl><dt>alpha</dt>
<dd>alpha level for 1-alpha confidence</dd>
<dt>n1</dt>
<dd>sample size for group 1</dd>
<dt>n2</dt>
<dd>sample size for group 2</dd>
<dt>sd.ratio</dt>
<dd>ratio of population standard deviations (sd2/sd1)</dd>
<dt>dist1</dt>
<dd>type of distribution for group 1 (1, 2, 3, 4, or 5)</dd>
<dt>dist2</dt>
<dd>type of distribution for group 2 (1, 2, 3, 4, or 5)<ul>
<li>1 = Gaussian (skewness = 0 and excess kurtosis = 0)</li>
<li>2 = platykurtic (skewness = 0 and excess kurtosis = -1.2)</li>
<li>3 = leptokurtic (skewness = 0 and excess kurtosis = 6)</li>
<li>4 = moderate skew (skewness = 1 and excess kurtosis = 1.5)</li>
<li>5 = large skew (skewness = 2 and excess kurtosis = 6)</li>
</ul></dd>
<dt>rep</dt>
<dd>number of Monte Carlo samples</dd></dl>

Arguments

Simulates confidence interval coverage probability for a median difference
in a 2-group design — sim.ci.median2

<dl>

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


<dt>n1</dt>
<dd>sample size for group 1</dd>


<dt>n2</dt>
<dd>sample size for group 2</dd>


<dt>sd.ratio</dt>
<dd>ratio of population standard deviations (sd2/sd1)</dd>


<dt>dist1</dt>
<dd>type of distribution for group 1 (1, 2, 3, 4, or 5)</dd>


<dt>dist2</dt>
<dd>type of distribution for group 2 (1, 2, 3, 4, or 5)<ul>
<li>1 = Gaussian (skewness = 0 and excess kurtosis = 0)</li>
<li>2 = platykurtic (skewness = 0 and excess kurtosis = -1.2)</li>
<li>3 = leptokurtic (skewness = 0 and excess kurtosis = 6)</li>
<li>4 = moderate skew (skewness = 1 and excess kurtosis = 1.5)</li>
<li>5 = large skew (skewness = 2 and excess kurtosis = 6)</li>
</ul></dd>


<dt>rep</dt>
<dd>number of Monte Carlo samples</dd>

</dl>

sim.ci.median2: Simulates confidence interval coverage probability for a median difference in a 2-group design

Description

Usage

Value

Arguments

Examples