Displaying 2 results from an estimated 2 matches for "factorx".
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2009 Feb 05
3
subset problem (reducing from six to two levels)
...(I am an R starter) with subsetting my
data set, but cannot figure out the solution: I want to subset a data set
from six to two levels, so that all analyses are done only with these two
remaining levels.
I tried
TOTAL<-read.delim('total.csv',header=T)
SUBSET.OF.TOTAL<-subset(TOTAL, FactorX %in% c("Level1","Level2"))
attach(SUBSET.OF.TOTAL)
but R does not eliminate the remaining levels of FactorX, just assigns 'not
available' to the data. Like this, the other levels still show up in plots
etc., but without data entries. Anybody got a solution how to subset...
2011 Jun 13
0
How to formulate an (effect-modifying) interaction with matching variable in a conditional logistic regression?
...hing variable
can't enter directly in the model but as an interaction with terms
that are in.
However, I have problems in formulating the correct model the term
that's already in the model is a factor. I am using treatment
contrasts and the problem is that if I write:
update(model, . ~ . + factorX:matchingvariableY)
then I get one extra level for the level that is contained in the
intercept which is conditioned away, and I get numerical problems. I
show an example below using data from Hosmer and Lemeshow's Applied
Logistic Regression (2nd ed. p.230 onwards)
I can solve the problem by...