crt.varexplore

This function can be used to help select a plausible value for the variance/SD of the
random intercept for cluster in a cluster randomized trial with a binary outcome.
Based on user-supplied values of the outcome proportions in the two arms,
the function outputs, for a range of possible values of the SD of the
random intercept, the intervals within which we expect about 95% of the cluster-level
proportions to lie in each arm.

Power and sample size calculations for a variety of study designs and
outcomes. Methods include t tests, ANOVA (including tests for interactions,
simple effects and contrasts), proportions, categorical data (chi-square tests
and proportional odds), linear, logistic and Poisson regression, alternative
and coprimary endpoints, power for confidence intervals, correlation
coefficient tests, cluster randomized trials, individually randomized group
treatment trials, multisite trials, treatment-by-covariate interaction effects
and nonparametric tests of location. Utilities are provided for
computing various effect sizes. Companion package to the book
"Power and Sample Size in R", Crespi (2025, ISBN:9781138591622).
Further resources available at <https://powerandsamplesize.org/>.

Catherine M. Crespi

powertools

Power and Sample Size Tools

Zichen Liu

Kristen M. McGreevy

crt.varexplore function

<dl><dt>pc</dt>
<dd>The probability of the outcome in control clusters.</dd>
<dt>pt</dt>
<dd>The probability of the outcome in treatment clusters.</dd>
<dt>print</dt>
<dd>Whether or not to print the results in a table; defaults to TRUE. To retrieve the results even when print = FALSE, assign the function output to an object.</dd></dl>

Arguments

Variance exploration for cluster randomized trials with binary outcomes — crt.varexplore

<dl>

<dt>pc</dt>
<dd>The probability of the outcome in control clusters.</dd>


<dt>pt</dt>
<dd>The probability of the outcome in treatment clusters.</dd>


<dt>print</dt>
<dd>Whether or not to print the results in a table; defaults to TRUE. To retrieve the results even when print = FALSE, assign the function output to an object.</dd>

</dl>

crt.varexplore: Variance exploration for cluster randomized trials with binary outcomes

Description

Usage

Value

Arguments

Details

Examples