ci.lc.stdmean.ws: Confidence interval for a standardized linear contrast of...

In statpsych: Statistical Methods for Psychologists

Confidence interval for a standardized linear contrast of means in a within-subjects design

Description

Computes confidence intervals for two types of population standardized linear contrast of means (unweighted standardizer and level 1 standardizer) in a within-subjects design. Equality of variances is not assumed, but the correlations among the repeated measures are assumed to be approximately equal.

Usage

ci.lc.stdmean.ws(alpha, m, sd, cor, n, q)

Arguments

alpha	alpha level for 1-alpha confidence
m	vector of estimated means for levels of within-subjects factor
sd	vector of estimated standard deviations for levels of within-subjects factor
cor	average estimated correlation of all measurement pairs
n	sample size
q	vector of within-subjects contrast coefficients

Value

Returns a 2-row matrix. The columns are:

• Estimate - estimated standardized linear contrast

• adj Estimate - bias adjusted standardized linear contrast estimate

• SE - standard error

• LL - lower limit of the confidence interval

• UL - upper limit of the confidence interval

References

\insertRef

Bonett2008statpsych

Examples

m <- c(33.5, 37.9, 38.0, 44.1)
sd <- c(3.84, 3.84, 3.65, 4.98)
q <- c(.5, .5, -.5, -.5)
ci.lc.stdmean.ws(.05, m, sd, .672, 20, q)

# Should return:
#                           Estimate  adj Estimate        SE        LL         UL
# Unweighted standardizer: -1.301263     -1.266557 0.3147937 -1.918248 -0.6842788
# Level 1 standardizer:    -1.393229     -1.337500 0.3661824 -2.110934 -0.6755248

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