idmact_comp {idmact}

Interpreting Differences in Mean ACT Scores at the Composite Level

Description

The idmact_comp() function calculates and interprets differences in ACT composite scores. The function operates in the following steps:

1. Increment raw scores for one or more subjects for each student to obtain adjusted raw scores.

2. Map adjusted raw scores to adjusted scale scores using the form's raw score to scale score map.

3. Obtain each examinee's adjusted composite scale score by averaging the adjusted scale scores across subjects.

4. Calculate the adjusted and unadjusted mean composite scale scores across all observations.

5. Compute the difference between the adjusted and unadjusted mean composite scale scores.

Usage

idmact_comp(
  df = NULL,
  df_map = NULL,
  raw,
  inc,
  map_raw,
  map_scale,
  mcent_subj = function(x) mean(x, na.rm = TRUE),
  mcent_obs = function(x) round(sum(x)/length(x)),
  mcent_comp = function(x) mean(x, na.rm = TRUE),
  na.rm.max = TRUE
)

Arguments

df

A data frame containing raw scores (optional). If provided, the 'raw' parameter should contain column names from this data frame.

df_map

A data frame mapping raw scores to scale scores.

raw

A list of raw scores for each subject, or column names from 'df' where raw scores are stored.

inc

A value or function used to increment raw scores for adjusted score calculation. This can be a single value or a list of values for each subject.

map_raw

Column names from 'df' or 'df_map' representing the domain of raw scores, or a list of such domains.

map_scale

Column names from 'df' or 'df_map' representing the range of scale scores, or a list of such ranges.

mcent_subj

A function summarizing scale scores at the subject level (default is mean with NA removal).

mcent_obs

A function summarizing scale scores at the examinee level (default is round(mean)).

mcent_comp

A function summarizing composite level scale scores (default is mean with NA removal).

na.rm.max

A boolean indicating whether to remove NA values when computing maximum raw and scale values in the mapping.

Details

By default, the function parameters align with the method presented in Schiel (1998). However, you can specify arbitrary anonymous functions for different implementations.

Value

A list containing composite and subject level results. "composite_results" includes the difference between the adjusted and unadjusted mean composite scale scores (deltac), the mean adjusted and unadjusted composite scale scores (mscale), and a list of individual adjusted and unadjusted composite scale scores (scale). "subject_results" includes the outcomes from idmact_subj for each subject.

References

Schiel, J. C. (1998). Interpreting differences in ACT composite scores (ACT Research Report Series 98-1). ACT, Inc. URL: https://www.act.org/content/dam/act/unsecured/documents/ACT_RR98-01.pdf

Examples

# Example 1: Using df and df_map
df <- data.frame(raw1 = c(1, 2, 3), raw2 = c(1, 1, 1))
df_map <- data.frame(map_raw1 = c(1, 2, 3),
                     map_scale1 = c(20, 21, 22),
                     map_raw2 = c(1, 1, 1),
                     map_scale2 = c(20, 20, 20))
comp_mean <- idmact_comp(df = df,
                         df_map = df_map,
                         raw = c("raw1", "raw2"),
                         inc = 1,
                         map_raw = c("map_raw1", "map_raw2"),
                         map_scale = c("map_scale1", "map_scale2"))

# Example 2: Using lists
raw = list(list(1, 2, 3, 4, 5), list(1, 1, 1, 1, 1))
inc = list(1 , 1)
map_raw = list(list(1, 2, 3, 4, 5))
map_scale = list(list(20, 21, 22, 23, 24))
comp_mean <- idmact_comp(raw = raw,
                         inc = inc,
                         map_raw = map_raw,
                         map_scale = map_scale)