I would appreciate any suggestions on which function to use to write subsequent functions analysing combinations of treatments.

This refers to experimental trials of medical treatments.  I want to write routines to analyse various comparisons (combinations)

So .... if 5 treatments are available (t01, t02, t03, t04 and t05) I want to write a general routine that works out all possible combinations, without repeats.  The other complication is that I want to be able to designate any one of the treatments as the common comparator such that all other treatments are compared to it.

For example, if I designate t04 as the common comparator then I want it to give me back some sort of vector or matrix with results

t01, t04
t02, t04
t03, t04
t05, t04

In my research I've found functions such as combinations and permutations in gtools, and also choose().  I suspect these could be coerced to provide the correct output but I may be missing a specific, or more flexible package that will produce this.

Any suggestions most welcome.

Thanks

Jim

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Dr. Jim Maas
University of East Anglia
Norwich, UK

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