item_discrim: Item Discrimination of Moodle Grade Report

In Lightbridge-KS/moodleStats: Analysis of Moodle Quiz Report

Item Discrimination of Moodle Grade Report

Description

Calculate Item Discrimination Index of Moodle Grade Report (see Details).

Usage

item_discrim(
  data,
  cor_method = c("pearson", "kendall", "spearman"),
  conf.level = 0.95
)

Arguments

data	(GradesReport) A data frame of class "GradesReport"
cor_method	(Character) A character string indicating which correlation coefficient is to be used for the test. One of "pearson", "kendall", or "spearman", can be abbreviated.
conf.level	(Numeric) Confidence level for the returned confidence interval. Currently only used for the Pearson product moment correlation coefficient if there are at least 4 complete pairs of observations.

Details

Item discrimination index (r) is a measure of how well an item is able to distinguish between examinees who are knowledgeable and those who are not. It is a pairwise point-biserial correlation between the score of each questions ("Q" columns) and total score of the quiz ("Grade" column).

item_discrim() calculate the correlation by stats::cor.test() function using Pearson's correlation coefficient (by default), then summarize each parameters into a data frame by broom::tidy(). Different types of correlation can be specified by cor_method argument.

Value

A data frame of Item Discrimination Index for each questions.

References

• What is Item Discrimination Index.

Examples

library(moodleStats)
# Prepare
grades_df_preped <- prep_grades_report(grades_df)

# Calculate
item_discrim(grades_df_preped)

Lightbridge-KS/moodleStats documentation built on April 7, 2022, 8:14 p.m.