Dear readers
I would like to make General Linear Model (GLM) for the following data set
http://louise.hoffman.googlepages.com/fuel.csv
The code I have written is
fuelData<-read.table('fuel.csv',header=TRUE, sep=',')
n<-dim(fuelData)[1]
xOnes<- matrix(1,nrow=n,ncol=1)
x<-cbind(xOnes,fuelData[,3])
y<-fuelData[,4]
theta<-((t(x)%*%x)^(-1))%*%t(x)%*%y
which gives
> theta
[,1]
[1,] 215.8374077
[2,] 0.1083491
When I do it in Matlab I get theta to be
79.69
0.18
which is correct. ~79 is the crossing of the y-axis.
Have I perhaps written theta wrong? The formula for theta is
(alpha,beta)^T = (x^T * x)^(-1) * x^T * Y
where ^T means transposed.
Can someone see where the mistake is?
Hugs,
Louise
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