[R] Regression and data types

[Gavin Simpson]

On Fri, 2008-09-26 at 13:17 +0100, GRANT Lewis wrote:
> Dear All
> I have three data sets, X1, X2 and Y. X1 is data, X2 and Y were
> generated in (different) R programs. All three vectors have one column
> of 60 data points.
> I am using the code lm(Y~X1)$coef and lm(Y~X2)$coef. 

Others have replied with an answer to your question. I just wanted to
suggest you don't rummage around in R model objects taking what you like
using '$'. 9 times out of 10 you'll get what you want, but that last
remaining time will have you rubbing your head in confusion at best, at
worst, answers may be just plain wrong.

Use extractor functions, such as coef() instead:

coef(lm(Y ~ X1))

G

> The first returns
> two values, an intercept and a slope, but the second returns 60 values.
> I suspect there is something in the "type" of X2 such that it forces the
> regression to do something different, but I can't work this out.
> Please help!
> Lewis
> 
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