# [R] Sub_scribe and a question

Philippe Grosjean phgrosje at ulb.ac.be
Mon Apr 30 11:01:19 CEST 2001

```Hello,

I would do like this: if the slope is a, and it is perfectly known, just
substract a*x from y. If you assume a relationship like y = a*x + b +
epsylon with epsylon having a normal distribution (0, sigma), then, y - a*x
should have a normal distribution (b, sigma), and the mean value of computed
y - a*x should simply be a good estimate of b, the intercept you are looking
for.

Berst Regards,

Philippe Grosjean

>Dear all,

>I am trying to get an estimate of the intercept for a linear model.  In
>this case, I know the slope of the model, can anyone tell me how to
>constrain the formula in lm() so that it only estimates the intercept
>not the slope?  Many thanks in advance,

>Sincerely,

>Liqing Zhang
>Dept. of Eco. Evol. Biol.
>Univ. of CA, Irvine
>email: lzhang at uci.edu

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