[Rasch] One partial-credit item or multiple dichotomous items?

Stuart Luppescu slu at ccsr.uchicago.edu
Tue Mar 3 08:42:11 EST 2015

Hello Fellow Raschies, I'm working on a test with some partial-credit 
items. The coding is something like 0: Did not understand at all; 1: 
Understood incompletely; 2: Understood completely.
I'm debating with the test developers about whether to make these 
individual items scored {0, 1, 2} or two dichotomous items: item 1: 
understood at least partially; item 2: understood completely. Is there 
an advantage to using one or the other approach?
Also, if we go with the two-dichotomous-item approach, how should the 
second item be scored if the student did not understand the question at 
all? That is, does it make a difference if the two items are scored 0, 
0; or 0, omitted?

Stuart Luppescu

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