|
|
Non-Positive Definite Between Level M... |
|
Message/Author |
|
Anonymous posted on Saturday, April 23, 2005 - 2:53 pm
|
|
|
I am trying to develop multiple level path analysis. When I have a restricted number of variables (n=6), I am able to perform the analysis. However, I discovered theoretical reasons to disaggregate a few of the measures, but not enough for Multilevel SEM. When I do this, I end up with a non-positive definite matrix at the between level. Any suggestions as to why and how to fix this problem? My level-2 n=29 and my level-1 n=447. There are two variables at level-2 and eight level-1 variables. I can't understand why the disaggregation would generate such problems. Any thoughts? |
|
Anonymous posted on Saturday, April 23, 2005 - 5:24 pm
|
|
|
I was able to figure out a proper start value that did the trick. |
|
|
I have a model with four factors with three indicators each (one with four), collected in 16 organisations. I am using TYPE=COMPLEX to account for the nesting of the data. I have received the following warning: "THE STANDARD ERRORS OF THE MODEL PARAMETER ESTIMATES MAY NOT BE TRUSTWORTHY FOR SOME PARAMETERS DUE TO A NON-POSITIVE DEFINITE FIRST-ORDER DERIVATIVE PRODUCT MATRIX. THIS MAY BE DUE TO THE STARTING VALUES BUT MAY ALSO BE AN INDICATION OF MODEL NONIDENTIFICATION. THE CONDITION NUMBER IS -0.142D-16. PROBLEM INVOLVING THE FOLLOWING PARAMETER: Parameter 16, PSC BY PSC1_3 THIS IS MOST LIKELY DUE TO HAVING MORE PARAMETERS THAN THE NUMBER OF CLUSTERS MINUS THE NUMBER OF STRATA WITH MORE THAN ONE CLUSTER." This happens both when I use all cases (i.e. including missing values, N = 1730) and complete cases (i.e. restricted to those with complete data, N = 1521). What does this mean - what kind of "strata" does Mplus refer to? Your help is very much appreciated. Thanks a lot! |
|
|
Dear Linda, dear Bengt, referring to my post from May, 27th - do you have a suggestion of why this happens? To what kind of "strata" does Mplus refer to? I have meanwhile run the model applying WLSMV because my indicators are 5-point-Likert type items. In this model, I do not get the above message. Can I consider this an indication that WLSMV is more appropriate for my data? Would this answer my above question? Thanks & kind regards! |
|
|
Your run probably has more than 16 parameters which is the number of clusters - this gives the message. If you have less than 16 Between-level parameters you should be ok and can use MLR or WLSMV. |
|
Back to top |
|
|