meta.ave.mean2: Confidence interval for an average mean difference from...

In dgbonett/vcmeta: Varying Coefficient Meta-Analysis

Confidence interval for an average mean difference from 2-group studies

Description

Computes the estimate, standard error, and confidence interval for an average mean difference from two or more 2-group studies. A Satterthwaite adjustment to the degrees of freedom is used to improve the accuracy of the confidence intervals. Equality of variances within or across studies is not assumed.

Usage

meta.ave.mean2(alpha, m1, m2, sd1, sd2, n1, n2, bystudy = TRUE)

Arguments

alpha	alpha level for 1-alpha confidence
m1	vector of estimated means for group 1
m2	vector of estimated means for group 2
sd1	vector of estimated SDs for group 1
sd2	vector of estimated SDs for group 2
n1	vector of group 1 sample sizes
n2	vector of group 2 sample sizes
bystudy	logical to also return each study estimate (TRUE) or not

Value

Returns a matrix. The first row is the average estimate across all studies. If bystudy is TRUE, there is 1 additional row for each study. The matrix has the following columns:

• Estimate - estimated effect size

• SE - standard error

• LL - lower limit of the confidence interval

• UL - upper limit of the confidence interval

• df - degrees of freedom

References

\insertRef

Bonett2009avcmeta

Examples

m1 <- c(7.4, 6.9)
m2 <- c(6.3, 5.7)
sd1 <- c(1.72, 1.53)
sd2 <- c(2.35, 2.04)
n1 <- c(40, 60)
n2 <- c(40, 60)
meta.ave.mean2(.05, m1, m2, sd1, sd2, n1, n2, bystudy = TRUE)

# Should return:
#         Estimate        SE        LL       UL        df
# Average     1.15 0.2830183 0.5904369 1.709563 139.41053
# Study 1     1.10 0.4604590 0.1819748 2.018025  71.46729
# Study 2     1.20 0.3292036 0.5475574 1.852443 109.42136

dgbonett/vcmeta documentation built on July 12, 2024, 3:12 p.m.