[R] fitted.values less than observed values

Federico Calboli f.calboli at imperial.ac.uk
Tue Aug 4 13:18:19 CEST 2009

Hi All,

I have some data where the dependent variable is a score, low (1:3) or  
high (8:9), and the independent variables are 21 genotypic markers.  
I'm fitting a logistic regression on the whole dataset after  
transforming the score to 0/1 and normal linear regression on the high  
and low subsets.

I all cases I have a numer of cases of data 'duplications', i.e.  
different individuals with the same score and the same genotype at the  
21 markers.

When I do:

mod$fitted.values I get a number of fitted values corresponding to the  
umber of unique lines in the dataset. Is there a way to have the  
fitted  values match the observation, even though some are duplicated  
and so have the same fitted value? I could do it by hand but it's  
laborious and I'd venture there is a better way.



Federico C. F. Calboli
Department of Epidemiology and Public Health
Imperial College, St. Mary's Campus
Norfolk Place, London W2 1PG

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

f.calboli [.a.t] imperial.ac.uk
f.calboli [.a.t] gmail.com

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