Multinomial multilevel: numeric warning
Posted: Fri Dec 11, 2015 4:53 pm
Hello,
I carried out a multinomial multilevel analysis in MLwiN, by using 2nd order PQL. My dependent variable is contraceptive use and consists of three categories:
(1) using no method (n = 3,328)
(2) using natural methods (n = 1,450)
(3) using hormonal/barrier methods (n = 8,693)
The analysis runs just fine when I estimate my models with the third category (using hormonal/barrier methods) as the reference group. However, if I run the same models with the first/second category as the reference group, the models only configure if use 1st order MQL. If I switch to 2nd order PQL, I get the following error: "IGLS/RIGLS NUMERIC WARNING. SSP matrix for fixed part has gone negative definite - a reconstruction to the nearest non-negative form has been used. Numeric warnings can be suppressed by setting an option on the Estimation Control, IGLS/RIGLS panel."
I tried the following solutions:
- Click "Yes" to continue the estimation, but it goes on until my estimates reach number over one billion.
- When I activate the option "suppress numeric warning", my estimates look like this: 1.#Q0(0.000)
- Allowing negative variances (also in the IGLS/RIGLS panel) doesn't work either, I get the same error
- I looked for a solution on your website (http://www.bristol.ac.uk/cmm/software/s ... rrors.html), but I cannot get my head around it.
Can anyone help me with this?
Thank you in advance!
Rozemarijn
I carried out a multinomial multilevel analysis in MLwiN, by using 2nd order PQL. My dependent variable is contraceptive use and consists of three categories:
(1) using no method (n = 3,328)
(2) using natural methods (n = 1,450)
(3) using hormonal/barrier methods (n = 8,693)
The analysis runs just fine when I estimate my models with the third category (using hormonal/barrier methods) as the reference group. However, if I run the same models with the first/second category as the reference group, the models only configure if use 1st order MQL. If I switch to 2nd order PQL, I get the following error: "IGLS/RIGLS NUMERIC WARNING. SSP matrix for fixed part has gone negative definite - a reconstruction to the nearest non-negative form has been used. Numeric warnings can be suppressed by setting an option on the Estimation Control, IGLS/RIGLS panel."
I tried the following solutions:
- Click "Yes" to continue the estimation, but it goes on until my estimates reach number over one billion.
- When I activate the option "suppress numeric warning", my estimates look like this: 1.#Q0(0.000)
- Allowing negative variances (also in the IGLS/RIGLS panel) doesn't work either, I get the same error
- I looked for a solution on your website (http://www.bristol.ac.uk/cmm/software/s ... rrors.html), but I cannot get my head around it.
Can anyone help me with this?
Thank you in advance!
Rozemarijn