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Thanks Bill. You make 2 very good points there. The possible reversal of association is something we will have to think carefully about - it hadn't occurred to me, but now you point it out, it seems obvious! I also had some concerns about the analysis being limited to 2 time points and the age ...

Hi Bill
We believe the relationship between use of technology and child development score to be non-linear; at both time points. The first set of measures are taken when the children are about 4 years old. It appears that up to a point, more technology use is associated with better developmental ...

I am trying to fit a model to a data set where data has been collected at 2 occasions; at baseline and follow-up. The outcome, a measure of child development, is numerical. The key predictor is a measure of use of technology by the child, also numerical. These variables are available both at ...

Many thanks Bill - very helpful as always. I think that defining a faculty, and one department per faculty as bases and using dummies for the rest sounds like the best way forward.
There are reasons to think that there is very little variation between faculties, so I will also try the 24-dummies ...

I have been asked to run a model of student exam data, with multiple entries per student. The repeated measures will form the lower level, and the students the higher level, of a 2-level hierarchy.

I have various student-level variables that I need to include: gender, ethnicity etc. I also need to ...

That does indeed help Bill - it's exactly what I needed to know. Many thanks.

I have been asked to run a model in which individuals are nested within divisions of an organisation, and divisions are nested within departments.

I am not sure how to treat the upper levels of the hierarchy. I currently have received data from about 96% of the divisions (about 250 in total), which ...

Thanks Bill - I did not think of the implications of using Level 2 predictors to potentially reduce the number of model levels.

I am running a 2-level model with several hundred thousand level-1 units but only about 70 level-2 units. I have already identified a set of level-1 predictors for inclusion, and am considering which, if any, predictors to add in at level-2.

I can identify about 9 individual L-2 predictors whose ...

Thanks Bill - good to know that the structure may not be the constraint I thought it might be. I take your point about the random slopes - I will have to give that some careful consideration.
John