grimmer_map_total_n: GRIMMER-testing with hypothetical group sizes

Description

When reporting group means, some published studies only report the total sample size but no group sizes corresponding to each mean. However, group sizes are crucial for GRIMMER-testing.

In the two-groups case, grimmer_map_total_n() helps in these ways:

It creates hypothetical group sizes. With an even total sample size, it incrementally moves up and down from half the total sample size. For example, with a total sample size of 40, it starts at 20, goes on to 19 and 21, then to 18 and 22, etc. With odd sample sizes, it starts from the two integers around half.
It GRIMMER-tests all of these values together with the group means.
It reports all the scenarios in which both "dispersed" hypothetical group sizes are GRIMMER-consistent with the group means.

All of this works with one or more total sample sizes at a time. Call audit_total_n() for summary statistics.

Usage

grimmer_map_total_n(
  data,
  x1 = NULL,
  x2 = NULL,
  sd1 = NULL,
  sd2 = NULL,
  dispersion = 0:5,
  n_min = 1L,
  n_max = NULL,
  constant = NULL,
  constant_index = NULL,
  ...
)

Value

A tibble with these columns:

x, the group-wise reported input statistic, is repeated in row pairs.
n is dispersed from half the input n, with n_change tracking the differences.
both_consistent flags scenarios where both reported x values are consistent with the hypothetical n values.
case corresponds to the row numbers of the input data frame.
dir is "forth" in the first half of rows and "back" in the second half. "forth" means that x2 from the input is paired with the larger dispersed n, whereas "back" means that x1 is paired with the larger dispersed n.
Other columns from grimmer_map() are preserved.

Arguments

data: Data frame with string columns x1, x2, sd1, and sd2, as well as numeric column n. The first two are reported group means. sd1 and sd2 are reported group SDs. n is the reported total sample size. It is not very important whether a value is in x1 or in x2 because, after the first round of tests, the function switches roles between x1 and x2, and reports the outcomes both ways. The same applies to sd1 and sd2. However, do make sure the x* and sd* values are paired accurately, as reported.
x1, x2, sd1, sd2: Optionally, specify these arguments as column names in data.
dispersion: Numeric. Steps up and down from half the n values. Default is 0:5, i.e., half n itself followed by five steps up and down.
n_min: Numeric. Minimal group size. Default is 1.
n_max: Numeric. Maximal group size. Default is NULL, i.e., no maximum.
constant: Optionally, add a length-2 vector or a list of length-2 vectors (such as a data frame with exactly two rows) to accompany the pairs of dispersed values. Default is NULL, i.e., no constant values.
constant_index: Integer (length 1). Index of constant or the first constant column in the output tibble. If NULL (the default), constant will go to the right of n_change.
...: Arguments passed down to grimmer_map(). (NOTE: Don't use the items argument. It currently contains a bug that will be fixed in the future.)

Summaries with <code>audit_total_n()</code>

You can call audit_total_n() following up on grimmer_map_total_n() to get a tibble with summary statistics. It will have these columns:

x1, x2, sd1, sd2, and n are the original inputs.
hits_total is the number of scenarios in which all of x1, x2, sd1, and sd2 are GRIMMER-consistent. It is the sum of hits_forth and hits_back below.
hits_forth is the number of both-consistent cases that result from pairing x2 and sd2 with the larger dispersed n value.
hits_back is the same, except x1 and sd1 are paired with the larger dispersed n value.
scenarios_total is the total number of test scenarios, whether or not both x1 and sd1 as well as x2 and sd2 are GRIMMER-consistent.
hit_rate is the ratio of hits_total to scenarios_total.

References

Bauer, P. J., & Francis, G. (2021). Expression of Concern: Is It Light or Dark? Recalling Moral Behavior Changes Perception of Brightness. Psychological Science, 32(12), 2042–2043. https://journals.sagepub.com/doi/10.1177/09567976211058727

Allard, A. (2018). Analytic-GRIMMER: a new way of testing the possibility of standard deviations. https://aurelienallard.netlify.app/post/anaytic-grimmer-possibility-standard-deviations/

Examples

Run this code

# Run `grimmer_map_total_n()` on data like these:
df <- tibble::tribble(
  ~x1,    ~x2,    ~sd1,   ~sd2,   ~n,
  "3.43", "5.28", "1.09", "2.12", 70,
  "2.97", "4.42", "0.43", "1.65", 65
)
df

grimmer_map_total_n(df)

# `audit_total_n()` summaries can be more important than
# the detailed results themselves.
# The `hits_total` column shows all scenarios in
# which both divergent `n` values are GRIMMER-consistent
# with the `x*` values when paired with them both ways:
df %>%
  grimmer_map_total_n() %>%
  audit_total_n()

# By default (`dispersion = 0:5`), the function goes
# five steps up and down from `n`. If this sequence
# gets longer, the number of hits tends to increase:
df %>%
  grimmer_map_total_n(dispersion = 0:10) %>%
  audit_total_n()

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