score.multiple.choice {psych}R Documentation

Score multiple choice items and provide basic test statistics

Description

Ability tests are typically multiple choice with one right answer. score.multiple.choice takes a scoring key and a data matrix (or data.frame) and finds total or average number right for each participant. Basic test statistics (alpha, average r, item means, item-whole correlations) are also reported.

Usage

score.multiple.choice(key, data, score = TRUE, totals = FALSE, ilabels = NULL, missing = TRUE, impute = "median", digits = 2,short=TRUE)

Arguments

key A vector of the correct item alternatives
data a matrix or data frame of items to be scored.
score score=FALSE, just convert to right (1) or wrong (0).
score=TRUE, find the totals or average scores and do item analysis
totals total=FALSE: find the average number correct
total=TRUE: find the total number correct
ilabels item labels
missing missing=TRUE: missing values are replaced with means or medians
mising=FALSE missing values are not scored
impute impute="median", replace missing items with the median score
impute="mean": replace missing values with the item mean
digits How many digits of output
short short=TRUE, just report the item statistics,
short=FALSE, report item statistics and subject scores as well

Details

Basically combines score.items with a conversion from multiple choice to right/wrong.

The item-whole correlation is inflated because of item overlap.

Value

scores Subject scores on one scale
missing Number of missing items for each subject
item.stats scoring key, response frequencies, item whole correlations, n subjects scored, mean, sd, skew, kurtosis and se for each item
alpha Cronbach's coefficient alpha
av.r Average interitem correlation

Author(s)

William Revelle

See Also

score.items, omega

Examples

data(iqitems)
iq.keys <- c(4,4,3,1,4,3,2,3,1,4,1,3,4,3)
score.multiple.choice(iq.keys,iqitems)
#just convert the items to true or false 
iq.tf <- score.multiple.choice(iq.keys,iqitems,score=FALSE)
describe(iq.tf)  #compare to previous results


[Package psych version 1.0-68 Index]