On 12/16/2009 03:58 PM, whitaker m. (mw1006) wrote: > Hi, > I am trying to create a set of dummy variables to use within a multiple > linear regression and am unable to find the codes within the manuals. > > For example i have: > Price Weight Clarity > IF VVS1 VVS2 > 500 8 1 0 0 > 1000 5.2 0 0 1 > 864 3 0 1 0 > 340 2.6 0 0 1 > 90 0.5 1 0 0 > 450 2.3 0 1 0 > > Where price is dependent upon weight (single value in each observation) and > clarity (split into three levels, IF, VVS1, VVS2). > I am having trouble telling the program that clarity is a set of 3 dummy > variables and keep getting error messages, what is the correct way? >
Without an example of your code, it's a bit difficult. But it might be easier to use one variable "clarity" with three possible values (IF, VVS1, VVS2), defined as a factor. lm(Price ~ Weight + Clarity) should then do the trick (unless you explicitly want to use a different dummy coding than the default) Stephan ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
