size.ci.ratio.mean.ps: Sample size for a paired-samples mean ratio confidence...

In statpsych: Statistical Methods for Psychologists

Sample size for a paired-samples mean ratio confidence interval

Description

Computes the sample size required to estimate a ratio of population means with desired confidence interval precision in a paired-samples design. Set the correlation planning value to the smallest value within a plausible range for a conservatively large sample size. This function requires planning values for each mean and the sample size requirement is very sensitive to these planning values. Set the variance planning value to the largest value within a plausible range for a conservatively large sample size.

Usage

size.ci.ratio.mean.ps(alpha, var, m1, m2, cor, r)

Arguments

alpha	alpha level for 1-alpha confidence
var	planning value of average variance of the two measurements
m1	planning value of mean for measurement 1
m2	planning value of mean for measurement 2
cor	planning value for correlation between measurements
r	desired upper to lower confidence interval endpoint ratio

Value

Returns the required sample size

Examples

size.ci.ratio.mean.ps(.05, 400, 150, 100, .7, 1.2)

# Should return:
# Sample size
#          21
 

statpsych documentation built on Sept. 11, 2024, 7:42 p.m.