Simulates confidence interval coverage probability for a standardized mean difference in a 2-group design
Source:R/statpsych1.R
sim.ci.stdmean2.Rd
Performs a computer simulation of confidence interval performance for two types of standardized mean differences in a 2-group design (see ci.stdmean2). Sample data for each group can be generated from five different population distributions. All distributions are scaled to have a standard deviation of 1.0 for group 1.
Arguments
- alpha
alpha level for 1-alpha confidence
- n1
sample size for group 1
- n2
sample size for group 2
- sd2
population standard deviation for group 2
- 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)
1 = Gaussian (skewness = 0 and excess kurtosis = 0)
2 = platykurtic (skewness = 0 and excess kurtosis = -1.2)
3 = leptokurtic (skewness = 0 and excess kurtosis = 6)
4 = moderate skew (skewness = 1 and excess kurtosis = 1.5)
5 = large skew (skewness = 2 and excess kurtosis = 6)
- d
population standardized mean difference
- rep
number of Monte Carlo samples
Value
Returns a 1-row matrix. The columns are:
Coverage - Probability of confidence interval including population std mean difference
Lower Error - Probability of lower limit greater than population std mean difference
Upper Error - Probability of upper limit less than population std mean difference
Ave CI Width - Average confidence interval width
Examples
sim.ci.stdmean2(.05, 20, 20, 1.5, 3, 4, .75, 5000)
#> Coverage Lower Error Upper Error Ave CI Width Ave Est
#> Unweighted Standardizer 0.9182 0.0522 0.0296 1.341751 0.7837115
#> Group 1 Standardizer 0.9478 0.0282 0.0240 1.812745 0.7823249
# Should return (within sampling error):
# Coverage Lower Error Upper Error Ave CI Width Ave Est
# Unweighted Standardizer 0.9058 0.0610 0.0332 1.342560 0.7838679
# Group 1 Standardizer 0.9450 0.0322 0.0228 1.827583 0.7862640