[R] fitting some form of linear model with bimodal distribution of dependent variable

[Federico Calboli]

Hi All,

I have a parameter that is bimodal, and I want to get some sort of linear model done with it

results = some.linear.function(bimodal.param ~ factor1 + some other stuff, mydata)

I want to see if factor 1 matters (it has 3 levels, of of which can be taken as baseline), i.e:

summary(results)

Coefficients:
            Estimate Std. Error t value Pr(>|t|)   
(Intercept) -2.108522   0.936666  -2.251   0.0272 
factor1-1        0.769314   0.273368   2.814   0.0062 
factor1-2        0.149841   0.198976   0.753   0.4537   

[the numbers are made up]

I am not clear which function, if any, could handle such situation. Any suggestions? I tried glm with family = quasi binomial, but it's obviously wrong if no other reason that it does not accept the bimodal parameter (it wants it to be 0s and 1s).

Cheers

Federico





--
Federico C. F. Calboli
Neuroepidemiology and Ageing Research
Imperial College, St. Mary's Campus
Norfolk Place, London W2 1PG

Tel +44 (0)20 75941602   Fax +44 (0)20 75943193

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