sim.ci.median2 {statpsych} | R Documentation |
Simulates confidence interval coverage probability for a median difference in a 2-group design
Description
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.
Usage
sim.ci.median2(alpha, n1, n2, sd.ratio, dist1, dist2, rep)
Arguments
alpha |
alpha level for 1-alpha confidence |
n1 |
sample size for group 1 |
n2 |
sample size for group 2 |
sd.ratio |
ratio of population standard deviations (sd2/sd1) |
dist1 |
type of distribution for group 1 (1, 2, 3, 4, or 5) |
dist2 |
type of distribution for group 2 (1, 2, 3, 4, or 5)
|
rep |
number of Monte Carlo samples |
Value
Returns a 1-row matrix. The columns are:
Coverage - Probability of confidence interval including population median difference
Lower Error - Probability of lower limit greater than population median difference
Upper Error - Probability of upper limit less than population median difference
Ave CI Width - Average confidence interval width
Examples
sim.ci.median2(.05, 20, 20, 2, 5, 4, 5000)
# Should return (within sampling error):
# Coverage Lower Error Upper Error Ave CI Width
# 0.952 0.027 0.021 2.368914