adjusted_cronbach_alpha: Adjusted Cronbach Alpha
In melissavanbussel/Analyze-Scantron: Analyze your multiple choice test

Description Usage Arguments Details Value Note See Also

Finds the adjusted Cronbach Alpha of the test.

1	adjusted_cronbach_alpha(exam, check_format = TRUE)

`exam`	A data.frame object containing a test that follows the formatting of a typical Scantron file.
`check_format`	a logical value (default = TRUE) indicating whether the "exam" object should be tested for correct formatting.

Cronbach Alpha is a measure of the reliability of a test. Its value can range from 0 to 1. Higher values are better. It should be noted, however, that increasing the number of questions on a test will always increase the reliability of the test. Thus, the Adjusted Cronbach Alpha is a measure of what the reliability of the test would be if the test had had 50 questions. This makes it easy to compare reliabilities across tests of different lengths.

Returns a numeric value corresponding to the adjusted Cronbach Alpha of the test.

The argument "exam" must be in the format of a typical Scantron results file. Column 1 should correspond to ID (e.g., student number); column 2 should correspond to DEPT (e.g., MATH); column 3 should correspond to COURSE CODE (e.g., 1051); the remaining columns should each correspond to one of the questions on the test. The header of the data frame should contain the column names, and row 1 of the data frame should contain the answer key for the test. For example, if you had an exam with 25 students and 40 questions, the data.frame object should have 26 rows and 43 columns.

The "check_format" argument defaults to null. If this is left as null, the function will call the num_choices_per_item function, which will do its best to guess the number of options for each question. This is done by looking at the student answers and finding the "largest" answer for each question. For example, if at least one student answered "E", but no students answered "F", the function would guess that there were 5 options for that question.

cronbach_alpha

melissavanbussel/Analyze-Scantron documentation built on May 10, 2019, 1:19 a.m.