[R] lines and glm

Jan P. Smit jps at srres.com
Thu Apr 8 13:37:51 CEST 2004


Dear R-helpers,

I'm a beginner using R 1.8.1 on Windows 2000. I'm trying to replicate some
examples in Franses' & Paap's Quantitative Models in Marketing Research. 

> t <- 1:1000
> e1 <- rnorm(1000)
> e2 <- rnorm(1000)
> x <- 0.0001*t+e1
> y2 <- -2+x+e2
> y <- ifelse(y2>0,1,0)
> 
> plot(x, y, pch = 16, col = "darkblue",
+      main = expression(paste("Scatter diagram of ", italic(y[t]), "
against ",
+          italic(x[t]))),
+      xlab = expression(italic(x[t])),
+      ylab = expression(italic(y[t])))
> lines(glm(y ~ x, family = binomial))

Error in xy.coords(x, y) : x and y lengths differ

However, 

> length(x)
[1] 1000
> length(y)
[1] 1000

as it should be.

I'm sure I must be missing something obvious, but it is not clear to me
(after reading the Introduction, FAQ and the relevant functions help pages)
what.

Sincerely,

Jan Smit




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