Hi,
I want to do regression in each group. I made the group the following way. Now
I want to run regression in each of the three groups..
Suppose ,
x<-c(0.5578196,6.5411662,13.2728619,2.0217271,6.7216176,3.37220617,2.5773252,7.2600583,15.3731026,3.4140288,8.1335874,
15..6476637,4.3014084,9.1224379,18.5605355,4.7448394,11.9296663,18.5866354,12.3797674,18.7572812,2.70433816,2.88924220,
2.94688208,3.37154364,2.26311786,3.31002593)
y<-c(18.63654,233.55387,152.61107,103.49646,234.55054,14.2767453,160.78742,150.35391,223.89225,168.55567,190.51031,
227.68339,152.42658,208.70115, 223.91982, 221.70702, 213.71135,168.0199,
222.69040,228.49353, 164.95750,243.18828,
229.94688,313.37154364,202.263786,139.31002593)
n<-length(x)
m<-3;
r<-8;
c<-r*(m-1);
g1<-rep(1:(m-1),each=r);
g<-c(g1,rep(m,n-c))
xg<-split(x,g);
yg<-split(y,g);
Now if I write lm(yg~xg) then it won't work. Please advice how to proceed.
Thanks in advance.
Bhargab
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Did you read the error message? Generally saying "doesn't work" will elicit undesirable responses. Now would be a good time to read the Posting Guide: http://www.R-project.org/posting-guide.html Including: "Say exactly what happened, including any error messages you received. " > lm(yg~xg) Error in model.frame.default(formula = yg ~ xg, drop.unused.levels = TRUE) : invalid type (list) for variable 'yg' You need to offer lm an object that it can use. You actually shot yourself in the foot by turning your data into a list. It's not clear what you actually want, but perhaps this will move you a bit further along: dfg <- data.frame(y=unlist(yg), x=unlist(xg), g=g) lm(y ~ x | g, data= dfg) Which would also be the same result as the following (without the detour to the yg and xg lists.) lm(y ~ x + g) It's also possible that what you really wanted was: lm(y ~ x + as.factor(g)) # which estimates mean differences of grp=2 and grp=3 from grp=1 with a common estimated slope of y on x. Or even lm(y ~ x * as.factor(g)) which gives you separate slopes and mean differences from those estimated for group 1 for groups 2 and 3 and is most consistent with the phrase "separate regressions in each of three groups". -- David Winsemius Heritage Laboratories On Jan 10, 2009, at 12:55 PM, Bhargab Chattopadhyay wrote:> Hi, > > > I want to do regression in each group. I made the group the > following way. Now I want to run regression in each of the three > groups.. > Suppose , > x<- > c > (0.5578196,6.5411662,13.2728619,2.0217271,6.7216176,3.37220617,2.5773252,7.2600583,15.3731026,3.4140288,8.1335874 > , > > 15 > .. > 6476637,4.3014084,9.1224379,18.5605355,4.7448394,11.9296663,18.5866354,12.3797674,18.7572812,2.70433816,2.88924220 > , > 2.94688208,3.37154364,2.26311786,3.31002593) > > y<- > c > (18.63654,233.55387,152.61107,103.49646,234.55054,14.2767453,160.78742,150.35391,223.89225,168.55567,190.51031 > , > 227.68339,152.42658,208.70115, 223.91982, 221.70702, > 213.71135,168.0199, 222.69040,228.49353, 164.95750,243.18828, > 229.94688,313.37154364,202.263786,139.31002593) > > n<-length(x) > m<-3; > r<-8; > c<-r*(m-1); > g1<-rep(1:(m-1),each=r); > g<-c(g1,rep(m,n-c)) > xg<-split(x,g); > yg<-split(y,g); > > Now if I write lm(yg~xg) then it won't work. Please advice how to > proceed. > > Thanks in advance. > > Bhargab > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
Bhargab Chattopadhyay <bhargab_1 <at> yahoo.com> writes:> > Hi, > > ?I want to?do regression?in each group. I made the group the following way.Now I want to run regression> in each of the three groups.. > Suppose , > w > > Now if I write lm(yg~xg) then it won't work. Please advice how to proceed. > > Thanks in advance. >The one-liner is mapply(function(x,y) lm(y~x,data=data.frame(x,y)),xg,yg, SIMPLIFY=FALSE) Perhaps easier to understand: results <- list() for (i in seq(along=xg)) { results[[i]] <- lm(yg[[i]]~xg[[i]]) } Ben Bolker
On 1/10/2009 12:55 PM, Bhargab Chattopadhyay wrote:> Hi, > > > I want to do regression in each group. I made the group the following way. Now I want to run regression in each of the three groups.. > Suppose , > x<-c(0.5578196,6.5411662,13.2728619,2.0217271,6.7216176,3.37220617,2.5773252,7.2600583,15.3731026,3.4140288,8.1335874, > 15..6476637,4.3014084,9.1224379,18.5605355,4.7448394,11.9296663,18.5866354,12.3797674,18.7572812,2.70433816,2.88924220, > 2.94688208,3.37154364,2.26311786,3.31002593) > > y<-c(18.63654,233.55387,152.61107,103.49646,234.55054,14.2767453,160.78742,150.35391,223.89225,168.55567,190.51031, > 227.68339,152.42658,208.70115, 223.91982, 221.70702, 213.71135,168.0199, 222.69040,228.49353, 164.95750,243.18828, > 229.94688,313.37154364,202.263786,139.31002593) > > n<-length(x) > m<-3; > r<-8; > c<-r*(m-1); > g1<-rep(1:(m-1),each=r); > g<-c(g1,rep(m,n-c)) > xg<-split(x,g); > yg<-split(y,g); > > Now if I write lm(yg~xg) then it won't work. Please advice how to proceed.mdf <- data.frame(y,x,g) lapply(split(mdf, g), function(X){lm(y ~ x, data = X)}) $`1` Call: lm(formula = y ~ x, data = X) Coefficients: (Intercept) x 76.11 10.85 $`2` Call: lm(formula = y ~ x, data = X) Coefficients: (Intercept) x 166.693 3.580 $`3` Call: lm(formula = y ~ x, data = X) Coefficients: (Intercept) x 218.412 -0.735> Thanks in advance. > > Bhargab > > > > > [[alternative HTML version deleted]] > > > > ------------------------------------------------------------------------ > > ______________________________________________ > 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.-- Chuck Cleland, Ph.D. NDRI, Inc. (www.ndri.org) 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894