[R] lm on group

[Adaikalavan Ramasamy]

You can guess by looking at class(g). It is a factor. It is NOT 
regressing on the mean of g (i.e. 2.5 and 7.5) and you could have 
changed g from (0,5] and (5,10] to A and B with the same results.

Read some books or help(lm) to get an idea of what the outputs mean.

Regards, Adai



newbieRRRRR wrote:
> Hi all,
>     
>       I have a quick question about lm on group, say I have:
> 
> x <- 1:10
> y <- x*3
> buckets <- seq(0, 10, by=5)
> g <- cut(x, buckets)
> summary(lm(y ~ g - 1))
> 
>       Coefficients:
>               Estimate Std. Error t value Pr(>|t|)    
> g(0,5]       9.000      2.121   4.243  0.00283 ** 
> g(5,10]   24.000      2.121  11.314 3.35e-06 ***
> 
>      What is it doing exactly? I guess the estimate is the mean of the y's
> in each group. 
> 
>      How about other stats.. what do they exactly mean when we do lm on
> groups? 
> 
> 
> Thanks a lot!