[R] FW: Reference category for explanatory factors

[Jason Ferris]

(Oops first mistake was posting to the wrong area)

I am not sure what is needed to be posted in terms of what I have done
but will explain nonetheless.

I am using the msm.package and trying to specify my reference category
for an outcome covariate.  The following command line works:

## age of respondent - using year5a: categorical
preg_fyear5a.msm<-msm(outcome~ipi, subject=id, data, qmatrix=crudemat,
exacttimes=TRUE, covariates=~factor(year5a))

However, in the dataset (data) the reference category 0 is a moderately
small cell, so I would like to change it to 1 which is much large.
There are 5 categories in the covariates year5a (0,1,2,3,4).

I have tried all sorts of approaches with 'ordered' and 'level' but no
love.

Cheers, 

Jase

PS. Operating in Win XP on a fast machine!

Jason Ferris
Research Officer
Australian Research Centre in Sex, Health and Society
Level 1, 215 Franklin St
Melbourne
VIC 3000
P: 61 (0)3 9285 5282
F: 61 (0)3 9285 5220