Elementary analysis of the items in a test and the test sumscores
based on Classical Test Theory.
Usage
tia(choices, key, ...)
Arguments
choices
The original responses to the items in the test: persons as
rows, items as columns. May contain NA.
key
A vector containing the key (correct answers) to the items in
choices. If not given, the function will check if all data are either
0, 1, or NA: if yes, NA are recoded as 0, else an error message is returned.
...
Other parameters that may be passed to sco or cov
Value
A list with three elements:
testlevel
A list of statistics at test level (currently, only
Cronbach's alpha, may be extended in future)
itemlevel
A matrix showing, for each item, the proportion of
correct responses, the correlation with the sum score, and the
alpha that the test would have if the item were dropped.
optionlevel
A matrix showing, for each possible choice in the
multiple-choice item, the proportion of responses given, and
the correlation with the sum score for the test (including the item).
The correct response is highlighted with asterisks.