st: Nonparametric Methods for Longitudinal Data

[Thomas Herold <thomasherold@gmx.net>]

Hello,

I am currently analysing a dataset on the influence of certain 
treatments on depression. We have three different treatment groups and 
five points of measurement.

The problem is that it has recently been discovered that the depression 
score we are working with can only be interpreted as ordinal data. 
What´s more, the resulting variable is far from being normally 
distributed - the data is just not suitable for parametric analysis.

Concerning the independent variables: Some of them change over time 
(e.g. financial situation), others are time-invariant (e.g. treatment).

Is there any nonparametric model for longitudinal data in STATA? Does 
anyone have any reading tips?

Thank you so much for your help,
Thomas


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