[R] lines and glm

[Uwe Ligges]

Jan P. Smit wrote:

> 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

You don't want plot y against x here, but something related to the glm 
object. I guess you are looking for
    abline(glm.object)

Uwe Ligges



> 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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