Sent from my iPhone
> On Jan 19, 2025, at 1:57 PM, David Winsemius <dwinsem...@comcast.net> wrote: > > I don’t understand why you don’t include the full text of the error. > > — > David > Sent from my iPhone > >> On Jan 19, 2025, at 10:00 AM, Sparks, John via R-help <r-help@r-project.org> >> wrote: >> >> Hello R-Helpers, >> >> I was looking into how to test whether the beta coefficient from a >> regression would be the same for two different groups contained in the >> dataset for the regression. >> >> When I put that question into google, AI returned a very nice looking answer >> (and a couple of variations on it). >> >> library(car) >> data <- data.frame(income = c(30, 45, 50, 25, 60, 55), >> education = c(12, 16, 14, 10, 18, 16), >> gender = c("Male", "Female", "Male", "Female", "Male", >> "Female")) >> model <- lm(income ~ education * gender, data = data) >> # Test if the beta for "education" is significantly different between genders >> test <- linearHypothesis(model, "genderMale - genderFemale = 0") That last line appears unlikely to be parsed correctly. In R a “=“ sign is interpreted as assignment whereas a “==“ (doubled equals) is a logical operator. Since I’ve only got a iPhone at hand I can’t test. In the future you should include full text of errors, preferably in the context in which they are returned. As an experiment I asked ChatGPT your question an it suggested library(car) data <- data.frame( income = c(30, 45, 50, 25, 60, 55), education = c(12, 16, 14, 10, 18, 16), gender = c("Male", "Female", "Male", "Female", "Male", "Female") ) model <- lm(income ~ education * gender, data = data) # Test if the effect of education differs by gender test <- linearHypothesis(model, "education:genderMale = 0") But I have the same concern about that code as I had with whatever your AI produced. — David >> print(test) >> >> This, however, produces an error that I can't find a way to resolve. >> >> Can this test actually be done in this manner, or is this a case of AI run >> amok. >> >> Guidance would be appreciated. >> --John Sparks >> >> >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide https://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide https://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.