Caoshang posted on Thursday, April 21, 2011 - 7:17 pm
Respect moderator: when I structure a exploratory LCA,\example as follow: 5 items(binary yes=1,no=0 item1=A,item2=B...item5=E); MODEL(3-class model,T=3) ŽÍ2(27.677) G2(21.003) AIC(57407.883) BIC(57534.981) df(14) Para(17) hand couputation: Number of parameters=(T-1)+T(A-1)+T(B-1)+T(C-1)+T(D-1)+T(E-1)=T(A+B+C+D+E-4)-1=17 Degrees of Freedom=df=(ABCDE-1)-17=14 The result is same with MPLUS5.1 couputation.But i noticed that the number of parameters(17) is bigger than the number of Degrees of Freeddom(14). Whether we can't get a set of optimal solution because of that. Should I restrict the parameters?(actually,i don't want to restrict them )So my question is if we insist the result, yet the result are reliable???
With five categorical indicators, the number of parameters in the H1 model is 31. This is the number you should be comparing the number of free parameters to. Your model is identified.
Caoshang posted on Saturday, April 23, 2011 - 7:10 pm
Respect Linda K. Muthen: Do I understand your meaning is that: you means the number of parameters(31) in H1 model(unrestricited model) is the sum of 'the number of free parameters(17)'and 'Degrees of Freedom'. my question is: 1,In my understanding of the past,if we want to get a set of optimal solution, the number of 'free parameters' should less than the number of 'Degrees of Freedom'.Am I wrong about the view?
2,you said 'This is the number you should be comparing the number of free parameters to'what's the meaning?why we should compare the number of 'parameters'and'free parameters' Is it about the identification problem of the model?