Comparing SMDs between independent studies

[Stable]

A function to compare standardized mean differences (SMDs) between studies. This function is intended to be used to compare the compatibility of original studies with replication studies (lower p-values indicating lower compatibility).

compare_smd(
  smd1,
  n1,
  se1 = NULL,
  smd2,
  n2,
  se2 = NULL,
  paired = FALSE,
  alternative = c("two.sided", "less", "greater", "equivalence", "minimal.effect"),
  null = 0,
  TOST = FALSE
)

Arguments

smd1, smd2

SMDs from study 1 & 2, respectively.

n1, n2

sample size(s) from study 1 & 2, respectively (can be 1 number or vector of 2 numbers).

se1, se2

User supplied standard errors (SEs). This will override the internal calculations.

paired

a logical indicating whether the SMD is from a paired or independent samples design. If a one-sample design, then paired must be set to TRUE.

alternative

a character string specifying the alternative hypothesis, must be one of "two.sided" (default), "greater", "less", "equivalence" (TOST), or "minimal.effect" (TOST). You can specify just the initial letter.

null

a number indicating the null hypothesis. For TOST, this would be equivalence bound.

TOST

Defunct: use alternative argument. Logical indicator (default = FALSE) to perform two one-sided tests of equivalence (TOST).

Value

A list with class "htest" containing the following components:

  • "statistic": z-score.

  • "p.value": numeric scalar containing the p-value for the test under the null hypothesis.

  • "estimate": difference in SMD between studies.

  • "null.value": the specified hypothesized value for the null hypothesis.

  • "alternative": character string indicating the alternative hypothesis (the value of the input argument alternative). Possible values are "greater", "less", or "two-sided".

  • "method": Type of SMD.

  • "data.name": "Summary Statistics" to denote summary statistics were utilized to obtain results.

  • "smd": SMDs input for the function.

  • "sample_sizes": Sample sizes input for the function.

  • "call": the matched call.

Details

This function tests for differences between SMDs from independent studies (e.g., original vs replication).

See also

Other compare studies: boot_compare_cor(), boot_compare_smd(), compare_cor()