Smith, Phil wrote: > Folks: > > I'm having trouble doing a forward variable selection using step() > > First, I fit an initial model: > > fit0 <- glm ( est~1 , data=all, subset=c(n>=25) ) > > then I invoke step(): > > fit1 <- step( fit0 , scope=list(upper=est~ pcped + pchosp + pfarm > ,lower=est~1)) > > > I get the error message: Error in eval(expr, envir, enclos) : invalid > 'envir' argument > > I looked at the documention on step(). There is no 'envir' arguement. > > Can anyone shed light on what I'm doing wrong? > > Thanks, > Phil Smith > CDC > > >
Could be your "data" argument. ?all is a base function. Try re-naming to something else. Here's an example: set.seed(1) z <- all <- data.frame(x = rnorm(10), y = rnorm(10)) glm.all <- glm(y ~ 1, data = all) step(glm.all, list(upper = y ~ x, lower = y ~ 1)) # Start: AIC= 32.67 # y ~ 1 # # Error in eval(expr, envir, enclos) : invalid 'envir' argument glm.z <- glm(y ~ 1, data = z) step(glm.z, list(upper = y ~ x, lower = y ~ 1)) # Start: AIC= 32.67 # y ~ 1 # # Df Deviance AIC # <none> 10.295 32.669 # + x 1 8.834 33.139 # # Call: glm(formula = y ~ 1, data = z) # # Coefficients: # (Intercept) # 0.2488 # # Degrees of Freedom: 9 Total (i.e. Null); 9 Residual # Null Deviance: 10.29 # Residual Deviance: 10.29 AIC: 32.67 ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
