replicate.mean.ps {vcmeta}

Compares and combines paired-samples mean differences in original and follow-up studies

Description

This function computes confidence intervals from an original study and a follow-up study where the effect size is a paired-samples mean difference. Confidence intervals for the difference and average effect size are also computed. Equality of variances within or across studies is not assumed. A Satterthwaite adjustment to the degrees of freedom is used to improve the accuracy of the confidence intervals for the difference and average. The same results can be obtained using the meta.lc.mean.ps function with appropriate contrast coefficients. The confidence level for the difference is 1 – 2*alpha, which is recommended for equivalence testing.

Usage

replicate.mean.ps(
  alpha,
  m11,
  m12,
  sd11,
  sd12,
  cor1,
  n1,
  m21,
  m22,
  sd21,
  sd22,
  cor2,
  n2
)

Arguments

alpha

alpha level for 1-alpha confidence

m11

estimated mean for group 1 in original study

m12

estimated mean for group 2 in original study

sd11

estimated SD for group 1 in original study

sd12

estimated SD for group 2 in original study

cor1

estimated correlation of paired observations in orginal study

n1

sample size in original study

m21

estimated mean for group 1 in follow-up study

m22

estimated mean for group 2 in follow-up study

sd21

estimated SD for group 1 in follow-up study

sd22

estimated SD for group 2 in follow-up study

cor2

estimated correlation of paired observations in follow-up study

n2

sample size in follow-up study

Value

A 4-row matrix. The rows are:

• Row 1 summarizes the original study

• Row 2 summarizes the follow-up study

• Row 3 estimates the difference in mean differences

• Row 4 estimates the average mean difference

The columns are:

• Estimate - mean difference estimate (single study, difference, average)

• SE - standard error

• df - degrees of freedom

• t - t-value

• p - p-value

• LL - lower limit of the confidence interval

• UL - upper limit of the confidence interval

References

Bonett DG (2021). “Design and analysis of replication studies.” Organizational Research Methods, 24(3), 513–529. ISSN 1094-4281, doi:10.1177/1094428120911088.

Examples

replicate.mean.ps(.05, 86.22, 70.93, 14.89, 12.32, .765, 20, 
                       84.81, 77.24, 15.68, 16.95, .702, 75)

#  Should return:
#                     Estimate       SE        t            p  
# Original:              15.29 2.154344 7.097288 9.457592e-07 
# Follow-up:              7.57 1.460664 5.182575 1.831197e-06 
# Original - Follow-up:   7.72 2.602832 2.966000 5.166213e-03 
# Average:               11.43 1.301416 8.782740 1.010232e-10 
#                              LL       UL       df
# Original:             10.780906 19.79909 19.00000
# Follow-up:             4.659564 10.48044 74.00000
# Original - Follow-up:  3.332885 12.10712 38.40002
# Average:               8.796322 14.06368 38.40002