Marc Schwartz wrote:
For your application Harold I would consider converting the response to a factor while dichotomizing it so that summary will give a meaningful tableOn Wed, 2004-07-07 at 07:57, Doran, Harold wrote:
Dear List:
I have searched the archives and my R books and cannot find a method to transform a continuous variable into a binary variable. For example, I have test score data along a continuous scale. I want to create a new variable in my dataset that is 1=above a cutpoint (or passed the test) and 0=otherwise.
My instinct tells me that this will require a combination of the transform command along with a conditional selection. Any help is much appreciated.
Example:
a <- rnorm(20) b <- ifelse(a < 0, 0, 1)
a
[1] -1.0735800 -0.6788456 1.9979801 -0.4026760 0.1781791 -1.1540434 [7] -1.0842728 1.6042602 -0.7950492 -0.1194323 0.4450296 1.9269333 [13] -0.4456181 -0.8374677 -1.1898772 1.7353067 1.8619422 -0.1679996 [19] -0.2656138 -1.5529884
b
[1] 0 0 1 0 1 0 0 1 0 0 1 1 0 0 0 1 1 0 0 0
HTH,
Marc Schwartz
b <- factor(ifelse(a < 0, "Neg", "Pos"))
BTW, there are many examples like this in the notes for the short course that you took last summer :-)
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