If one knows y, x, and a, and wishes to estimate b in
y = a*x + b (+ random error presumably)
then surely the simplest procedure is
b.hat <- mean(y-a*x)
Is it not so?
cheers,
Rolf
On 09/12/11 08:09, Ben Bolker wrote:
R. Michael Weylandt<michael.weylandt<at> gmail.com> writes:
Fit y-b without an intercept? (which you do by adding "+ 0" or "- 1"
to the model formula) Not sure if this is the optimal result, but it
will give you a pretty reasonable answer.
This seems backward. The OP has the slope and wants the intercept.
On Thu, Dec 8, 2011 at 10:52 AM, Alaios<alaios<at> yahoo.com> wrote:
I have a formula of the form
y=ax+b
I know everything except b.
How I can ask R to do fitting to find only the value of b?
I already know the lm() but it always return both an intercept point
(b) and the a.
Or:
lm (y~1,offset=a*x,data= ...)
or
lm(y-a*x~1,data=...) [not sure this will evaluate the full
expresson on the LHS but it might]
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