I'm looking for some more sophisticated analytical methods for assessing age-at-exposure effects. The literature I'm reading typically polytomizes age into groups, which I'd like to use as a last resort. I'd like to model age-at-exposure as a continuous variable and calc risk per year. It's possible the effects I'm looking at are non-linear. I'd rather not calculate an average slope across age... this would attenuate effects I expect to see.
Let's say I have access to data that are both cross-sectional and longitudinal, but only two time points for the latter right now.
Has anyone come across statistical methods that would serve these purposes?