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Compares and combines single mean in original and follow-up studies

Source: R/meta_rep.R
replicate.mean1.Rd

This function computes confidence intervals for a single mean from an original study and a follow-up study. Confidence intervals for the difference between the two means and average of the two means are also computed. Equality of variances 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 confidence level for the difference is 1 – 2*alpha, which is recommended for equivalence testing.

For more details, see Chapter 4 of Bonett (2021, Volume 5).

Usage

replicate.mean1(alpha, m1, sd1, n1, m2, sd2, n2)

Arguments

alpha

alpha level for 1-alpha confidence

m1

estimated mean in original study

sd1

estimated SD in original study

n1

sample size in original study

m2

estimated mean in follow-up study

sd2

estimated SD in follow-up study

n2

sample size for 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 means

  • Row 4 estimates the average mean

The columns are:

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

  • SE - standard error

  • LL - lower limit of the confidence interval

  • UL - upper limit of the confidence interval

  • df - degrees of freedom

References

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

Bonett DG (2021). Statistical Methods for Psychologists, Vol 1-5, https://dgbonett.sites.ucsc.edu/.

Examples

replicate.mean1(.05, 21.9, 3.82, 40, 25.2, 3.98, 75)
#>                       Estimate        SE        LL        UL     df
#> Original:                21.90 0.6039950 20.678305 23.121695 39.000
#> Follow-up:               25.20 0.4595708 24.284285 26.115715 74.000
#> Original - Follow-up:    -3.30 0.7589567 -4.562527 -2.037473 82.630
#> Average:                 23.55 0.3794784 22.795183 24.304817 82.633

# Should return:
#                       Estimate        SE        LL        UL    df
# Original:                21.90 0.6039950 20.678305 23.121695 39.00
# Follow-up:               25.20 0.4595708 24.284285 26.115715 74.00
# Original - Follow-up:    -3.30 0.7589567 -4.562527 -2.037473 82.63
# Average:                 23.55 0.3794784 22.795183 24.304817 82.63