Message-ID: <434A2C70.7010209@statistik.uni-dortmund.de>
Date: 2005-10-10T08:55:12Z
From: Uwe Ligges
Subject: details about lm()
In-Reply-To: <434A21B2.6020106@7d4.com>
vincent at 7d4.com wrote:
> Domenico Cozzetto a ??crit :
>
>
>>Dear all,
>>I'd like to get a linear regression of some data, and impose that the line
>>goes through a given point P. I've tried to use the lm() method in the
>>package "stats", but I wasn't able to specify the coordinates of the point
>>P. Maybe I should use another method?
>
>
> add directly P in your data is also a way
No!
Please, both of you, consult a basic textbook on linear regression.
You can transform the data (linear) so that P becomes (0,0), after that
you can estimate the slope without intercept by specifying
lm(y ~ x - 1)
The slope estimate is still valid while your intercept can be calculated
afterwards.
Uwe Ligges
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