score.multiple.choice {psych} | R Documentation |
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.
score.multiple.choice(key, data, score = TRUE, totals = FALSE, ilabels = NULL, missing = TRUE, impute = "median", digits = 2,short=TRUE)
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 |
Basically combines score.items
with a conversion from multiple choice to right/wrong.
The item-whole correlation is inflated because of item overlap.
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 |
William Revelle
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