[R] Step function
mjpocern at ouray.cudenver.edu
Wed Nov 29 19:07:31 CET 2000
I am having problem using the step function for a linear regression model. I've created an initial model containing only the intercept. Then using the step function, I've selected three variables to be considered for the model.
> x0.lm<- lm(MEDV~1, data = x)
Analysis of Variance Table
Df Sum Sq Mean Sq F value Pr(>F)
Residuals 505 42716 85
> step(x0.lm, ~ CRIM + ZN + RM)
Start: AIC= 2246.51
MEDV ~ 1
Error in eval(expr, envir, enclos) : Object "MEDV" not found
I am not clear as to why the MEDV object ( the variable I am trying to predict) is not found. I receive an identical message using the command > step(x0.lm).
I am using R version 1.1.1. I can run all the examples successfully. Also, I realize that there are differences in the algorithms, but I can run the code above on Splus version 5.
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