Author Topic: Including Case PID in Outputs  (Read 425 times)

georgeha

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Including Case PID in Outputs
« on: November 27, 2013, 08:43:18 PM »
My objective is to keep the ID from the data file connected to the person estimates in the outputs from the Show Cases (and from the Export Scoreddata) commands (so I can subsequently read the output into SAS easily, thereby connecting the estimates to my other datasets from other analyses of these persons). To do this, I assumed, after reading the manual, I need to specify PID in the FORMAT command, but when I specify PID (as FORMAT PID 1-8 time 9 responses 11-40), ConQuest crashes. If I specify it with any other name, such as "ID" (as in this: (as FORMAT ID 1-8 time 9 responses 11-40), ConQuest runs fine, but the output ID is just the order ID, not the 8 digit ID from my data file.
 
I read that ConQuest has to sort the cases when PID is used (they are already sorted), but I only am examining about 500 cases, so I wouldn't expect a sort to crash the program.  The model is unidimensional and converges fairly quickly (79 iterations in less than 10 seconds).

Am I missing something?

Cheers

Eveline Gebhardt

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Re: Including Case PID in Outputs
« Reply #1 on: November 27, 2013, 11:47:11 PM »
Hello

This is a bug in CQ that we do not understand well yet. It only appeared in more recent versions of CQ. Conquest usually does not crash when you use PID, but it seems to stop. However, if you wait a long time, it will run in the end. We are trying to fix this problem.

The quickest solution for now is to leave it out or to use ID as you suggested. I usually add a sequential ID number to my data file that I can use for merging with the output files.

I hope this helps.

Eveline

georgeha

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Re: Including Case PID in Outputs
« Reply #2 on: December 01, 2013, 08:22:21 PM »
Ah, thanks, Eveline. Good to know. I hope that after I purchase the software (I'm using the trial until my uni approves purchase), I can get updates when they come out. You're right--it doesn't really crash, it just keeps running.  I tried letting mine run for an hour (on my 16GB 2.9Ghz machine), but it still didn't finish, so I stopped it.

The other reason I wanted to keep PIDs was that I am comparing this unidimensional model with multidimensional models. In my multidim model, some of the cases are missing data on all the items in one or more of the dimensions.  For making model comparison, these cases should be eliminated from both the multidim and unidim models before I get my -2LL estimates.  Having a stable PID will lower chances of mistakes, but now that I know this is a bug, I can work with the ordering and just be extra careful :-)

Cheers!

George

Eveline Gebhardt

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Re: Including Case PID in Outputs
« Reply #3 on: December 06, 2013, 01:48:25 AM »
If you do not use keepcases or dropcases, the default ID that ConQuest gives in output files is the line number in your data. If the person in line 4 has all missing data, ID number 4 will be skipped in the output file, for example with WLEs. Always check carefully though, you won't be the first that mismatches data files ;)