score.multiple.choice {psych}

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,skew=FALSE)

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
missing=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

skew

Should the skews and kurtosi of the raw data be reported? Defaults to FALSE because what is the meaning of skew for a multiple choice item?

Details

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

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

The example data set is taken from the Synthetic Aperture Personality Assessment personality and ability test at https://www.sapa-project.org/.

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

if(require(psychTools)) {
data(psychTools::iqitems)
iq.keys <- c(4,4,4, 6,6,3,4,4,  5,2,2,4,  3,2,6,7)
score.multiple.choice(iq.keys,psychTools::iqitems)
#just convert the items to true or false 
iq.tf <- score.multiple.choice(iq.keys,psychTools::iqitems,score=FALSE)
describe(iq.tf)  #compare to previous results
}