How to use a function inside a regression formula
On 30/09/2011 2:07 PM, Jim Cheng wrote:
Hi,
How do I use a function inside a regression formula? When I tried to use
min() function inside a regression formula, I ran into errors. Here are
the commands to reproduce the error:
mydata<- read.csv(url("http://www.ats.ucla.edu/stat/r/dae/binary.csv"))
attach(mydata)
names(mydata)
mylm2 = lm(admit~gre+I(max(gpa,rank)))
*Error in model.frame.default(formula = admit ~ gre + I(max(gpa, rank)), :
variable lengths differ (found for 'I(min(gpa, rank))')*
min(gpa, rank) will be a length 1 vector. You want pmin(gpa, rank). (I haven't tried it in the regression, but it should work.) Duncan Murdoch
* * * * Regards, David [[alternative HTML version deleted]]
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