R/meta_ave.R
meta.ave.meanratio2.Rd
Computes the estimate, standard error, and confidence interval for a geometric average mean ratio 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.
meta.ave.meanratio2(alpha, m1, m2, sd1, sd2, n1, n2, bystudy = TRUE)
alpha level for 1-alpha confidence
vector of estimated means for group 1
vector of estimated means for group 2
vector of estimated SDs for group 1
vector of estimated SDs for group 2
vector of group 1 sample sizes
vector of group 2 sample sizes
logical to also return each study estimate (TRUE) or not
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
exp(Estimate) - exponentiated estimate
exp(LL) - lower limit of the exponentiated confidence interval
exp(UL) - upper limit of the exponentiated confidence interval
df - degrees of freedom
Bonett DG, Price RM (2020). “Confidence intervals for ratios of means and medians.” Journal of Educational and Behavioral Statistics, 45(6), 750--770. ISSN 1076-9986, doi:10.3102/1076998620934125 .
m1 <- c(7.4, 6.9)
m2 <- c(6.3, 5.7)
sd1 <- c(1.7, 1.5)
sd2 <- c(2.3, 2.0)
n1 <- c(40, 20)
n2 <- c(40, 20)
meta.ave.meanratio2(.05, m1, m2, sd1, sd2, n1, n2, bystudy = TRUE)
#> Estimate SE LL UL exp(Estimate) exp(LL)
#> Average 0.1759928 0.05738065 0.061437186 0.2905484 1.192429 1.063364
#> Study 1 0.1609304 0.06820167 0.024749712 0.2971110 1.174603 1.025059
#> Study 2 0.1910552 0.09229675 0.002986265 0.3791242 1.210526 1.002991
#> exp(UL) df
#> Average 1.337161 66.26499
#> Study 1 1.345965 65.69929
#> Study 2 1.461004 31.71341
# Should return:
# Estimate SE LL UL exp(Estimate)
# Average 0.1759928 0.05738065 0.061437186 0.2905484 1.192429
# Study 1 0.1609304 0.06820167 0.024749712 0.2971110 1.174603
# Study 2 0.1910552 0.09229675 0.002986265 0.3791242 1.210526
# exp(LL) exp(UL) df
# Average 1.063364 1.337161 66.26499
# Study 1 1.025059 1.345965 65.69929
# Study 2 1.002991 1.461004 31.71341