Search found 156 matches

by billb
Fri Jun 20, 2014 1:00 pm
Forum: MLwiN user forum
Topic: Logistic multilevel regression
Replies: 3
Views: 5889

Re: Logistic multilevel regression

Hi Shane, Saw your question and on the list. I might suggest asking MPlus why they interpret things differently here? Let's suppose one didn't fit level 2 in the model then the model is a straightforward logistic regression and level 2 variables are just standard fixed effects like level 1 variables...
by billb
Fri Jun 20, 2014 12:22 pm
Forum: MLwiN user forum
Topic: coefficient changes between logistic multilevel models
Replies: 1
Views: 3411

Re: coefficient changes between logistic multilevel models

Hi Shane, Interesting question. I guess one could look at the correlation between the various predictors prior to putting in the model as if you are trying to explain the contextual effect as being in reality compositional factors then there would be strong correlations. Even in a normal model If yo...
by billb
Tue Jun 03, 2014 8:54 am
Forum: MLwiN user forum
Topic: Random effects for level 2 covariates
Replies: 1
Views: 3408

Re: Random effects for level 2 covariates

Hi Maelsu2012, If you allow a level 2 covariate to be random at level 1 you are essentially saying that the within level 2 variability is different for different values of the level 2 predictor. This is perfectly acceptable and for example is a route for allowing a different level 1 variance for boy...
by billb
Fri May 23, 2014 1:16 pm
Forum: MLwiN user forum
Topic: INtervals & Tests - Error in p values
Replies: 2
Views: 4868

Re: INtervals & Tests - Error in p values

Hi SCEinShef, This is a misunderstanding of the Interval and Tests window. It will only give you a chi-squared test statistic and not a P value which you will need the tail areas window to calculate. The number +/- 95% sep is simply 1/2 the interval width i.e. in the case of Gender you have coeff 0....
by billb
Fri May 09, 2014 7:14 am
Forum: R2MLwiN user forum
Topic: Using R2MLwiN to write BUGS code
Replies: 3
Views: 6117

Re: Using R2MLwiN to write BUGS code

Hi Manny, Apologies half asleep when I wrote the earlier reply and read your code too quickly. The u terms in your model are simply higher level terms and so they are fine and clustering here is fine. The question is really whether one can construct a correlation between the 2 responses at level 1 w...
by billb
Fri May 09, 2014 7:04 am
Forum: R2MLwiN user forum
Topic: Using R2MLwiN to write BUGS code
Replies: 3
Views: 6117

Re: Using R2MLwiN to write BUGS code

Hi MannyGomez, There is a reason why we haven't implemented bivariate mixtures in the MLwiN -> BUGS interface. Basically BUGS struggles with covariance matrices that have constraints in them - in the case of the model you have one variance is constrained to 1 and what you have done in this part of y...
by billb
Thu Feb 06, 2014 9:48 am
Forum: MLwiN user forum
Topic: Re-parametrization in multivariate models (MCMC)
Replies: 2
Views: 4648

Re: Re-parametrization in multivariate models (MCMC)

Hi Nils, Lots of questions so here are some pointers: 1) Orthogonal reparameterization is in theory only of use when MLwiN has to use Metropolis Hastings i.e. when we don't have normal responses and it improves mixing as it gets around the correlations between the various fixed effects. If MLwiN can...
by billb
Wed Jan 15, 2014 1:42 pm
Forum: runmlwin user forum
Topic: Dummy as Random Slopes
Replies: 4
Views: 5939

Re: Dummy as Random Slopes

Hi, I am not sure what is happening here but I'd be happy to take a look at your spreadsheet. I am presuming that your grouping is not a level 5 variable as this would cause issues? Otherwise if you have coded your dummies correctly it shouldn't matter which is used and they should have the same DIC...
by billb
Thu Jan 09, 2014 1:30 pm
Forum: runmlwin user forum
Topic: MCMC starting values
Replies: 3
Views: 7499

Re: MCMC starting values

Hi Nils, Have been discussing your emails with Chris and we will look at why the starting values cause a crash and get back to you. It may be that your starting values are generating an initial position for the variance function which implies a negative variance for certain observations which would ...
by billb
Thu Nov 28, 2013 9:39 am
Forum: MLwiN user forum
Topic: Variance co-variance structure for repeated measures data
Replies: 1
Views: 3297

Re: Variance co-variance structure for repeated measures da

Depends what you mean here. Are you using ordered or unordered categories? Would suggest you read the manual chapters on ordered/unordered models in the MLwiN manual and see if this answers your question. The fact that
your data is repeated measures is probably irrelevant here. Bill.