Error: $ operator not defined for this S4 class

[Spike]

Hello,

I have tried to get the parameters of a mirt model on a test of 75 items with a sample size of 15,000. And naturally I used coef(object), which returned "Error: $ operator not defined for this S4 class"

Here is my sample code:

test_structure <- F1 = 1 - 25
                   F2 = 26 - 50
                   F3 = 51 - 75
                   COV = F1*F2, F2*F3, F1*F3'

dim_structure <- mirt::mirt.model(test_structure)

MOD2 <- mirt::mirt(dat, dim_structure, itemtype = '2PL', method = 'MHRM')

out <- coef(MOD2)

Does anyone have an opinion on the issue?

[Phil Chalmers]

This looks like pretty standard syntax, so I don't see why there would be a problem. Can you provide a reproducible example with these code?

Phil

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[TingJhen Jiang]

I have the same issue.

And after examination, I find out that it is because while I did not include library(mirt) before, I in fact called stats::coef instead of mirt::coef by calling coef().

Only mirt::coef works.

Spike於 2018年9月24日星期一 UTC+8下午8時06分58秒寫道：