1. Is this homework? -- we don't do homework. 2. This is not an R question -- posting to stats.stackexchange.com or other statistics websites is usually more appropriate for such non-R statistical questions
3. General approach: Combine all data; model it with both a simpler (fewer parameter, single slope) model and a more complex (separate slopes for different groups of data); test difference in models (e.g. via likelihood ratio which reduces to anova for the normal theory case). 4. Better approach: Ignore 3, because the test has not been pre-planned, suitable power has not been designed in, or the hypothesis is post hoc, etc., so that P values are therefore likely just nonsense with no sensible interpretation. The correct answer is: The slopes _are_ different (entropy is on my side here -- a very powerful ally that one should avoid messing with). The relevant question then becomes: Are they different enough to matter in your context (which if it's homework is -- who cares?) . 5. Perhaps the best approach: Ignore the rantings of a grumpy statistician and consult your local statistical resource for help, which you clearly need more of then can be provided here. Cheers, Bert On Wed, Mar 14, 2012 at 9:24 AM, Mark Leeds <marklee...@gmail.com> wrote: > Hi: I'm jot sure if it's exactly what you want but check out Hotelling's > paper from 1940. It > should be in the archives because I answered this question before ( not > from you ). > If you can't find it, I'll find the title .... actually, here's the title: > > Hotelling, The Selection of Variates For Use in Prediction with Some > Comments on the > General Problem of Nuisance Parameters", Annals of Mathematical Statistics, > 11, > 271-283. > > > > > On Wed, Mar 14, 2012 at 11:21 AM, Michael <comtech....@gmail.com> wrote: > >> How to test the statistical significance of the difference of two >> univariate Linear Regression betas? >> >> Hi all, >> >> There are two samples of data: D1 and D2. >> >> On data D1 we do a univariate Linear Regression and get the coefficient >> beta1. >> >> On data D2 we do a univariate Linear Regression and get the coefficient >> beta2. >> >> How do I test the statistical significance of (beta1-beta2)? >> >> Could you please recommend packages/commands in R for doing this? >> >> Thanks a lot! >> >> [[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. >> > > [[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 ______________________________________________ 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.