Hello everyone,
I am trying to undertake an item bifactor analysis of graded response data from
a questionnaire. I am using the mirt package, especially the bfactor
function.My dataset is called "data.items", it contains about 2000 observations
and 31 variables (variables represent the items in the questionnaire). The
items follow a Likert scale format and represent a level of satisfaction,
missing values are coded as NA). I am having trouble at the beginning of my
analysis, during the exploratory model fitting. The syntax and the error
message are as follows:
> bfactor(data.items,model=9)
Error in ESTIMATION(data = data, model = model, group = rep("all", nrow(data)),
:
index out of bounds
I get the same error when i try with: bfactor(data.items,9,itemtype="graded")
or bfactor(data.items,9,prev.cor=cor)
where cor is the correlationmatrix that i compute without the missing values.
If someone have an idea to suggest, do not hesitate.
Thank you.
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