# [R] How to draw a graph after model selection?

ahbu deliaquek1 at yahoo.com.sg
Wed Oct 3 16:21:40 CEST 2012

```I am very new to R and I basically used SPSS to do my model selection, which
I had used generalized linear model.

So my best model is P= D + T + L + T*L and there is a parameters table from
the SPSS output which I suppose I have to use the coefficients (column B) in
the table (as attached) when I draw my graph in R.

I want to draw a graph in R which x-axis is D, using the model and the
relevant coefficients. From what I read online, this is the code I've got
but I am not sure if it is correct as I keep getting "In Ops.factor((0.195),
dataT1\$T) : * not meaningful for factors" when I tried to sub in values."

plot(dataT1\$D, dataT1\$P, ylab = "Percentage carrion weight left", xlab =
"Day")
*T1 <- (0.205)*dataT1\$D + (0.195)*dataT1\$T + 0.227*       #DO I SUB IN MY
EQUATION HERE?#
p.average1 <- exp(T1) / (1 + exp(T1))
I1 <- order(dataT1\$D)
lines(dataT1\$D[I1],p.average1[I1],lwd=2, col="red")
p.Upp1 <- exp(T1 + 1.96*0.19215)/(1+exp(T1 + 1.96*0.19215))
p.Low1 <- exp(T1 - 1.96*0.19215)/(1+exp(T1 - 1.96*0.19215))
lines(dataT1\$D[I1], p.Upp1[I1], col="red")
lines(dataT1\$D[I1], p.Low1[I1], col="red")

I am supposed to draw a graph where I fix D and T and draw P against D. How
am I supposed to do that???

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