Hello Bert, This is definitely not for a homework problem. I am trying to estimate frequencies of mutations in different groups. The mutation frequencies can be modeled as a linear relation in cases of mixtures. So I have a lot of populations that follow the relationship -
y = alpha*A + beta*B and I want to estimate A and B; given y, alpha and beta. A and B are both vectors of the same size as y. Can you suggest where I can find some information about your suggestion #4...that is exactly what I was hoping to do. Thanks, Diviya On Mon, Mar 19, 2012 at 3:02 PM, Bert Gunter <gunter.ber...@gene.com> wrote: > 1. Homework assignment? We don't do homework here. > > 2. If not, a mixture model of some sort? I suggest you state the > context of the problem more fully. R has several packages to do > mixture modeling, if that's what you're trying to do. > > 3. In any case, this cannot be done with lm() (at least without tricks). > > 4. In your notation below, the "separate" regressions can be stacked > into a single constrained regression model. > > 5. You might do better to find local statistical help, as you may have > bitten off more than you can chew. > > -- Bert > > On Mon, Mar 19, 2012 at 11:29 AM, Diviya Smith <diviya.sm...@gmail.com> > wrote: > > Hello there, > > > > I am new to using regression in R. I wanted to solve a simple regression > > problem where I have 2 equations and 2 unknowns. > > > > So lets say - > > y1 = alpha1*A + beta1*B > > y2 = alpha2*A + beta2*B > > > > y1 <- runif(100000, 0,1) > > y2 <- runif(100000,0,1) > > > > alpha1 <- 0.6 > > alpha2 <- 0.75 > > > > beta1 <- 1-alpha1 > > beta2 <- 1-apha2 > > > > I now want this equation to estimate the values of A and B. Both A and B > > are constrained to be between (0,1). I would like to use lm with these > > constraints and I am having a little trouble in defining the equations > > correctly. Any help would be most appreciated. > > > > Thank you, > > Diviya > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@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. > > > > -- > > Bert Gunter > Genentech Nonclinical Biostatistics > > Internal Contact Info: > Phone: 467-7374 > Website: > > http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm > [[alternative HTML version deleted]] ______________________________________________ R-help@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.
