R: [R] lines and glm

[Guazzetti Stefano]

You probably mean something like:

 ti <- 1:1000
 e1 <- rnorm(1000)
 e2 <- rnorm(1000)
 x <- 0.0001*ti+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])))

 model<-glm(y ~ x, family = binomial)
 predProbs<-predict(model,data.frame(x=seq(min(x), max(x), length.out=100)), type="response")
 lines(seq(min(x), max(x), length.out=100), predProbs, col=2, lwd=2)



Note also that it is not a good idea to name "t" a R object, since the name is reserved for a special function.


Stefano


> -----Messaggio originale-----
> Da: Jan P. Smit [mailto:jps at srres.com]
> Inviato: giovedì 8 aprile 2004 13.38
> A: r-help at stat.math.ethz.ch
> Oggetto: [R] lines and glm
> 
> 
> 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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