Sorry, result is not the same, since our datasets are different. I also run lm() based on the dataset that used in glm(). THe results are exactly the same:
> summary(lm(Y ~ X + F)) Call: lm(formula = Y ~ X + F) Residuals: Min 1Q Median 3Q Max -0.53796 -0.16201 -0.08087 0.15080 0.47363 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 0.03723 0.08457 0.440 0.662267 X 0.51009 0.13036 3.913 0.000365 *** FB 1.82578 0.15429 11.833 2.6e-14 *** --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 0.2469 on 38 degrees of freedom Multiple R-squared: 0.9612, Adjusted R-squared: 0.9592 F-statistic: 471.1 on 2 and 38 DF, p-value: < 2.2e-16 =============== The dataset is given below: > cbind(Y,X,F) Y X F [1,] -0.28473266 -1.00 1 [2,] -0.59041310 -0.95 1 [3,] -0.50431754 -0.90 1 [4,] -0.60095969 -0.85 1 [5,] -0.45849905 -0.80 1 [6,] -0.48287208 -0.75 1 [7,] -0.49598666 -0.70 1 [8,] -0.08746758 -0.65 1 [9,] -0.18665177 -0.60 1 [10,] -0.01007210 -0.55 1 [11,] -0.45765308 -0.50 1 [12,] -0.27318684 -0.45 1 [13,] 0.07638855 -0.40 1 [14,] 0.27043727 -0.35 1 [15,] 0.26926216 -0.30 1 [16,] -0.43047783 -0.25 1 [17,] 0.40884468 -0.20 1 [18,] -0.14638563 -0.15 1 [19,] -0.31374179 -0.10 1 [20,] -0.15028159 -0.05 1 [21,] -0.12540519 0.00 1 [22,] 1.58015611 0.05 2 [23,] 1.68200774 0.10 2 [24,] 2.02821901 0.15 2 [25,] 2.02359285 0.20 2 [26,] 2.14133171 0.25 2 [27,] 2.06931685 0.30 2 [28,] 2.05561726 0.35 2 [29,] 2.35720999 0.40 2 [30,] 1.96134404 0.45 2 [31,] 2.26144356 0.50 2 [32,] 2.24454620 0.55 2 [33,] 2.55707426 0.60 2 [34,] 2.18732022 0.65 2 [35,] 1.90950697 0.70 2 [36,] 2.10371010 0.75 2 [37,] 2.18266009 0.80 2 [38,] 2.18490441 0.85 2 [39,] 2.45248295 0.90 2 [40,] 2.79851838 0.95 2 [41,] 1.83514341 1.00 2 -- View this message in context: http://r.789695.n4.nabble.com/regression-function-for-categorical-predictor-data-tp2532045p2532305.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.