Hi, Im fitting some simple linear models to data from the olympic running events with lm(Logtime~Logdistance), the models contain an intercept and one slope parameter. I have fitted a separate model for each years data and as the intercept changes very little between years i am trying to simplify the models so that they all have the same intercept (calculated from the mean of the previous intercepts). I have seen a few posts relating to zero intercepts but cannot figure out how to set to a specific value to the parameter. Any help would be greatly appreciated. Thanks. Chris. -- View this message in context: http://r.789695.n4.nabble.com/How-to-specify-a-fixed-intercept-for-linear-model-tp3072044p3072044.html Sent from the R help mailing list archive at Nabble.com.
Michael Bedward
2010-Dec-04 03:49 UTC
[R] How to specify a fixed intercept for linear model
The offset arg is your friend... x <- 1:10 y <- 42 + 2*x + rnorm(length(x), 0, 0.5) # we suspect the intercept might be 42 ! lm( y ~ 0 + x, offset=rep(42, length(x))) Michael On 4 December 2010 13:42, cborley87 <christopher.borley at students.plymouth.ac.uk> wrote:> > Hi, > > Im fitting some simple linear models to data from the olympic running events > with lm(Logtime~Logdistance), the models contain an intercept and one slope > parameter. > > I have fitted a separate model for each years data and as the intercept > changes very little between years i am trying to simplify the models so that > they all have the same intercept (calculated from the mean of the previous > intercepts). > > I have seen a few posts relating to zero intercepts but cannot figure out > how to set to a specific value to the parameter. > > Any help would be greatly appreciated. > > Thanks. > > Chris. > -- > View this message in context: http://r.789695.n4.nabble.com/How-to-specify-a-fixed-intercept-for-linear-model-tp3072044p3072044.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >