[R] lm help: using lm when one point is known (not y intercept)

[Seth Imhoff]

Hello-

My question is a short one.  How can I specify a single point which 
through the fitted linear model has to go through?  To illustrate my 
problem, the fit to following data must go through the point 
(-37.25(effect), 50(prob)).  Note: you can ignore the label column.

    Effect      Prob Label

1 -1143.75  7.142857     L

2  -572.75 21.428571     D

3  -223.75 35.714286    GL

4   123.25 50.000000    DG

5   359.75 64.285714     G

6   374.75 78.571429   DGL

7   821.75 92.857143    DL


Thanks in advance!

Seth Imhoff