Hi, everyone.

We are going to do a longitudinal follow-up study of three groups of children: a healthy normal comparison group, and two treatment groups. We are going to have 75 children per group, and are going to be assessing them at 18 months of age, 3 years, 5 years, and 7 years of age. It's going to be a long study!!

We have hypothesized that our two primary outcome variables will remain fairly constant at the four ages for the normal comparison group, and also for one of the treatment groups. We expect these two variables will decline over time for children in the last treatment group. We also want to see when does this decline occur (if it does in fact occur). It may be a constant decline over time, or it could be more pronounced at one of the age ranges (for example between 18 months and 3 years of age).

Initially, we thought that we'd just do a repeated measures MANCOVA, but now we are wondering if that will get at the question of when the decline occurs. Can the question of when the decline occurs be examined through "contrasts" for the time effect in the analysis? Can we even do this with SPSS?

Many thanks!

-- Susan Crawford, M.Sc. Research Coordinator Behavioural Research Unit Alberta Children's Hospital