Unexpected singularities in the Fisher Information matrix are encountered. There may be a quasi-complete separation in the data. Some parameter estimates will tend to infinity.
How to tackle the proplem |
(a) increase the sample size, by a lot;
=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD
(b) decrease the number of predictors; (c) decrease the number of categories in the ordinal outcome; (d) use a linear model (Least Squares Regression). You probably can't do (a). You should do (b) in any case, if you are including more than a few. The possibilities for (c) and (d) depend on information that you have not mentioned, such as the N, the k (predictors), and the success of prediction that you would reasonably expect ... which we could possibly judge if you mentioned details such as "predicting what from what?" -- Rich Ulrich > Date: Tue, 14 Jun 2016 00:32:58 -0700 > From: [hidden email] > Subject: spss ordinal regression > To: [hidden email] > > Unexpected singularities in the Fisher Information matrix are encountered. > There may be a quasi-complete separation in the data. Some parameter > estimates will tend to infinity. > How to tackle the proplem > > |
Other possibilities - - collapse some dependent variable categories - Use NOMREG - Use the STATS FIRTHLOG extension command, which fits a penalized logistic model On Tue, Jun 14, 2016 at 8:38 AM, Rich Ulrich <[hidden email]> wrote:
|
For some reason I do not see the OP on Nabble.
Are you sure you need ordinal regression? Try CATREG in SPSS. see whether there is a meaningful difference between MODEL fits with with ORDINAL specification and INTERVAL specifications. (You might also try a NOMINAL specification.) CATREG does a test between models with different assumptions about measurement level.
Art Kendall
Social Research Consultants |
Free forum by Nabble | Edit this page |