Seth Imhoff
2004-Nov-28 04:08 UTC
[R] lm help: using lm when one point is known (not y intercept)
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
John Fox
2004-Nov-28 04:49 UTC
[R] lm help: using lm when one point is known (not y intercept)
Dear Seth, You don't say which variable is the explanatory variable and which is the response, but assuming that prob is to be regressed on effect, you can fit lm(prob - 50 ~ I(effect + 37.25) - 1). That is you can shift the point through which the regression is to go to the origin and then force the regression through the origin. I hope this helps, John -------------------------------- John Fox Department of Sociology McMaster University Hamilton, Ontario Canada L8S 4M4 905-525-9140x23604 http://socserv.mcmaster.ca/jfox --------------------------------> -----Original Message----- > From: r-help-bounces at stat.math.ethz.ch > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Seth Imhoff > Sent: Saturday, November 27, 2004 11:09 PM > To: r-help at stat.math.ethz.ch > Subject: [R] lm help: using lm when one point is known (not y > intercept) > > 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