Author Topic: Can between-item MIRT substract with within-item MIRT?  (Read 416 times)

chiehyu

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Can between-item MIRT substract with within-item MIRT?
« on: April 27, 2016, 10:10:54 PM »
Hello, I have a question,

I ran a between-item MIRT and a within-item MIRT. I have some theories that two of my items contributed to two traits simultaneously.  Can I treat them as nested models and then subtract the deviance and AIC with the other to show the evidence which model fits better?

I attach my code, hope this will help people to judge. 

Here is my between-item MIRT code:

Title IRT_PC 16m 3_14_16 5DRPCM;
datafile \Users\Tom Chen\Desktop\asq3_16m.dat;
format id 1-5 responses 6-35;
labels << \Users\Tom Chen\Desktop\asq_labels.txt;
codes 2,1,0;
score (2,1,0) (2,1,0) () () () () !items(1-6);
score (2,1,0) () (2,1,0) () () () !items(7-12);
score (2,1,0) () () (2,1,0) () () !items(13-18);
score (2,1,0) () () () (2,1,0) () !items(19-24);
score (2,1,0) () () () () (2,1,0) !items(25-30);
model item + item*step;
set constraints=cases,warnings=no,update=yes;
export logfile >> asq16m5D_run1LOG.log;
export parameters >> asq16m5D_run1PRM.prm;
export reg_coefficients >> asq16m5D_run1REG.reg;
export covariance >> asq16m5D_run1COV.cov;
estimate!method=montecarlo,nodes=2000, converge=.005, stderr=quick,iter=1000;
reset;
datafile \Users\Tom Chen\Desktop\asq3_16m.dat;
format id 1-5 responses 6-35;
labels << \Users\Tom Chen\Desktop\asq_labels.txt;
codes 2,1,0;
score (2,1,0) (2,1,0) () () () () !items(1-6);
score (2,1,0) () (2,1,0) () () () !items(7-12);
score (2,1,0) () () (2,1,0) () () !items(13-18);
score (2,1,0) () () () (2,1,0) () !items(19-24);
score (2,1,0) () () () () (2,1,0) !items(25-30);
model item + item*step;
set constraints=cases,warnings=no,update=yes;
import init_parameters << asq16m5D_run1PRM.prm;
import init_reg_coefficients << asq16m5D_run1REG.reg;
import init_covariance << asq16m5D_run1COV.cov;
export logfile >> asq16m5D_run1LOG.log;
export parameters >> asq16m5D_run1PRM.prm;
export reg_coefficients >> asq16m5D_run1REG.reg;
export covariance >> asq16m5D_run1COV.cov;
estimate!method=montecarlo,nodes=2000, converge=.005, stderr=quick,iter=1000;
show ! estimates=latent, filetype=xlsx >> asq16m5D_run1SHOWLAT.xlsx;
show ! estimates=latent >> asq16m5D_run1SHOWLAT.lat;
show ! estimates=latent, tables=5 >> asqse16m_table5.lat;
itanal! filetype=xlsx >> asq16m5D_run1ITN.xlsx;
quit;


Here is my within-item MIRT code:

Title IRT_PC asq16m 3_15_16 5DRPCM_within;
datafile \Users\Tom Chen\Desktop\asq3_16m.dat;
format id 1-5 responses 6-35;
labels << \Users\Tom Chen\Desktop\asq_labels.txt;
codes 2,1,0;
score (2,1,0) (2,1,0) () () () () !items(1-6);
score (2,1,0) () (2,1,0) () () () !items(7-12);
score (2,1,0) () () (2,1,0) () () !items(13-18);
score (2,1,0) () () (2,1,0) (2,1,0) () !items(19);
score (2,1,0) () () () (2,1,0) () !items(20);
score (2,1,0) () () () (2,1,0) () !items(21);
score (2,1,0) () () () (2,1,0) () !items(22);
score (2,1,0) () () (2,1,0) (2,1,0) () !items(23);
score (2,1,0) () () () (2,1,0) () !items(24);
score (2,1,0) () () () () (2,1,0) !items(25-30);
model item + item*step;
set constraints=cases,warnings=no,update=yes;
export parameters >> asq16m5D_run1PRM.prm;
export reg_coefficients >> asq16m5D_run1REG.reg;
export covariance >> asq16m5D_run1COV.cov;
estimate!method=montecarlo,nodes=2000, converge=.005, stderr=quick,iter=1000;
reset;
datafile \Users\Tom Chen\Desktop\asq3_16m.dat;
format id 1-5 responses 6-35;
labels << \Users\Tom Chen\Desktop\asq_labels.txt;
codes 2,1,0;
score (2,1,0) (2,1,0) () () () () !items(1-6);
score (2,1,0) () (2,1,0) () () () !items(7-12);
score (2,1,0) () () (2,1,0) () () !items(13-18);
score (2,1,0) () () (2,1,0) (2,1,0) () !items(19);
score (2,1,0) () () () (2,1,0) () !items(20);
score (2,1,0) () () () (2,1,0) () !items(21);
score (2,1,0) () () () (2,1,0) () !items(22);
score (2,1,0) () () (2,1,0) (2,1,0) () !items(23);
score (2,1,0) () () () (2,1,0) () !items(24);
score (2,1,0) () () () () (2,1,0) !items(25-30);
model item + item*step;
set constraints=cases,warnings=no,update=yes;
import init_parameters << asq16m5D_run1PRM.prm;
import init_reg_coefficients << asq16m5D_run1REG.reg;
import init_covariance << asq16m5D_run1COV.cov;
export logfile >> asq16m5D_run1LOG.log;
export parameters >> asq16m5D_run1PRM.prm;
export reg_coefficients >> asq16m5D_run1REG.reg;
export covariance >> asq16m5D_run1COV.cov;
estimate!method=montecarlo,nodes=2000, converge=.005, stderr=quick,iter=1000;
show ! estimates=latent, filetype=xlsx >> asq16m5D_run1SHOWLAT.xlsx;
show ! estimates=latent >> asq16m5D_run1SHOWLAT.lat;
show ! estimates=latent, tables=5 >> asqse16m_table5.lat;
itanal! filetype=xlsx >> asq16m5D_run1ITN.xlsx;
quit;

Eveline Gebhardt

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Re: Can between-item MIRT substract with within-item MIRT?
« Reply #1 on: April 29, 2016, 06:35:33 AM »
Yes, these models are nested.