GRIM test for mean

Source: R/core-functions.R

This function tests whether a given mean (with a specific precision) can result from a sample of a given size based on integer responses to one or more items. The test is based on Brown & Heathers (2017).

GRIM_test(
  mean,
  n_obs,
  m_prec = NULL,
  n_items = 1,
  return_values = FALSE,
  return_list = FALSE,
  quiet = FALSE
)

Arguments

mean

The mean of the distribution

n_obs

The number of observations (sample size)

m_prec

The precision of the mean, as number of digits after the decimal point. If not provided, taken based on the significant digits of mean - so only needed if reported mean ends in 0

n_items

Number of items in scale, if distribution represents scale averages. Defaults to 1, which represents any single-item measure.

return_values

A logical value. ignored if return_list = TRUE. If FALSE (the default), the function returns a simple TRUE or FALSE. If TRUE, it returns a numeric vector of all possible means that are consistent with the parameters. If the test fails when return_values = TRUE, a warning is issued and the closest consistent mean is returned. If there are two equally close means, both are returned.

return_list

A logical value. If FALSE (the default), the function's return type is determined by return_values. If TRUE, the function instead returns a list containing two elements: a logical passed flag and a numeric vector values containing the relevant means.

quiet

Suppress warnings.

Value

The return type depends on the arguments. By default, a logical scalar (TRUE or FALSE). If return_values = TRUE, a numeric vector is returned. If return_list = TRUE, a list is returned.

References

Brown NJ, Heathers JA (2017). “The GRIM test: A simple technique detects numerous anomalies in the reporting of results in psychology.” Social Psychological and Personality Science, 8(4), 363–369.

Examples

# A sample of 28 integers cannot result in a mean of 5.19.
GRIM_test(mean = 5.19, n_obs = 28)
#> [1] FALSE

# To find the closest possible mean, set return_values to TRUE
GRIM_test(mean = 5.19, n_obs = 28, return_values = TRUE)
#> Warning: Mean 5.19 fails GRIM test - closest consistent value: 5.18
#> [1] 5.18

# To get a detailed list containing both the logical result and the values
GRIM_test(mean = 5.19, n_obs = 28, return_list = TRUE)
#> $passed
#> [1] FALSE
#> 
#> $values
#> [1] 5.18
#>