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| From | Yuval Arbel <yuval.arbel@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: Test for significance of the difference between knee locations? |
| Date | Thu, 18 Oct 2012 22:45:45 +0200 |
I forgot to mention that Age_sq is AgexAge If i'm not mistaken Jordan is from the medical field On Thu, Oct 18, 2012 at 10:36 PM, Roger B. Newson <r.newson@imperial.ac.uk> wrote: > What is the "knee" of a quadratic model? I never knew that they had knees > (although I might expect a 3-parameter linear spline to have a knee). > > Best wishes > > Roger > > Roger B Newson BSc MSc DPhil > Lecturer in Medical Statistics > Respiratory Epidemiology and Public Health Group > National Heart and Lung Institute > Imperial College London > Royal Brompton Campus > Room 33, Emmanuel Kaye Building > 1B Manresa Road > London SW3 6LR > UNITED KINGDOM > Tel: +44 (0)20 7352 8121 ext 3381 > Fax: +44 (0)20 7351 8322 > Email: r.newson@imperial.ac.uk > Web page: http://www.imperial.ac.uk/nhli/r.newson/ > Departmental Web page: > http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/ > > Opinions expressed are those of the author, not of the institution. > > > On 18/10/2012 21:25, Jordan Silberman wrote: >> >> Hi Stata folks, >> >> I'm searching for a method I can run in Stata that will allow me to >> test whether the location of the knee for one quadratic model >> significantly differs from that of another quadratic model. >> >> I have 2 quadratic models, each modeling a different category of >> healthcare costs as a function of age. Let's say, for illustrative >> purposes, that the knee of the first quadratic model occurs at age 45, >> and the knee for the second model occurs at age 55. >> >> Can anybody suggest a method for testing whether the former "knee age" >> differs significantly from the latter "knee age?" The idea is to test >> the hypothesis that there is a difference across the 2 models in the >> age at which the costs growth rate begins to increase. >> >> Any suggestions would be greatly appreciated. >> >> Thanks, >> Jordan >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/faqs/resources/statalist-faq/ >> * http://www.ats.ucla.edu/stat/stata/ >> > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ -- Dr. Yuval Arbel School of Business Carmel Academic Center 4 Shaar Palmer Street, Haifa 33031, Israel e-mail1: yuval.arbel@carmel.ac.il e-mail2: yuval.arbel@gmail.com * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/