I have the data from a study which comprises a number of organisms (5)
exposed to one of 4 concentrations of a test compound, with parameters of
interest being measured at 4 separate time points.
For each of 10+ parameters, I wish to find out whether there is a
significant effect due to the compound, and does the effect vary
significantly over time. Additionally, I am interested in the multivariate
case in order to make a generalisation about the overall effect of the
compound on the organisim
The data do not meet the assumptions for ANOVA and so preclude the use of
RM ANOVA or ANCOVA with time as a block or covariate respectively. For most
of the parameters measured, there does appear to be an effect due to time,
but it is not linear.
Initially, I considered Friedmans test, but this would not tell me about
the time effect and to do this, I would have to average the values at each
treatment\time to get one measurement and hence lose information about the
variability of the data.
Any suggestions on how best to analyse this data gratefully received
Thanks
Alan
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