Petr Pikal said: "The explanation is not for few lines of plain text short mail.
But maybe others will disagree." Not I -- you should consult your teachers or texts (as Petr said) for basic statistical questions. I'll add a nugget to Petr's reply, however: it is very often the case (for correlated regressors/covariates) that individual coefficients cannot and should not be interpreted -- the "fit" is merely a prediction engine.'' Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Thu, Sep 8, 2016 at 5:43 AM, Matti Viljamaa <mvilja...@kapsi.fi> wrote: > I’m trying to understand how to interpret the return values, specifically > “Coefficients:”, of R’s lm function. I’m using it with a dichotomic predictor > (mom_hs). > > lm(data$kid_score ~ data$mom_hs) returns > > Coefficients: > # (Intercept) data$mom_hs > # 77.55 11.77 > > I read that the (Intercept) value is the “y-intercept” value b, i.e. the y > value where the line intercept the y-axis. > > The second value is the value of the term m (or “slope”) in the equation of a > line y=mx+b. > > However, > > These two numbers also have the following interpretations: > > b or (Intercept) value is the same as: > The mean of those data$kid_score that have data$mom_hs == 0. > Why is this a valid interpretation? > > m or data$mom_hs value is the same as: > The difference of means between those data$kid_score that have data$mom_hs == > 1 > and those data$kid_score that have data$mom_hs == 0. > Why is this a valid interpretation? > > Can someone explain? > ______________________________________________ > 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 http://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 http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
