aguri posted on Monday, November 19, 2012 - 10:04 pm
Dear Dr. Muthen I am using MPLUS 3.11 to run a Latent Class Analysis. The database are from TIMSS 2007 about student attitudes to math, 12 items(Likert 4-point) and about 4000 test takers included.I try to make exploratary LCA to find how many classes would be approriate, two questions are bumped into: 1. the p-value of Likelihood Ratio Chi-Square from c(1) to c(3) are 1, when c(4), something showed up... THE MODEL ESTIMATION DID NOT TERMINATE NORMALLY DUE TO A NON-POSITIVE DEFINITE FISHER INFORMATION MATRIX. CHANGE YOUR MODEL AND/OR STARTING VALUES. .......
so I try to recode the data from 4-point to 2 categories (positive and negative orientation),and the result showed 5 classes is much better. I am not sure what happened when 4-point situations, and could I deal with the problem as description !!??(Do you recommend to change estimates method or setting starting value!?) 2. If I want to know which class level each test taker belongs to, what can I do !!?? THANKS A LOT
my code as reference ~ TITLE: LCA DATA: FILE IS test1115.dat; VARIABLE: NAMES ARE gender i1-i12 ; USEVARIABLES ARE i1-i12; CLASSES = c (3); CATEGORICAL = i1-i12; ANALYSIS: TYPE = MIXTURE; OUTPUT: TECH1 TECH7;