Call: g1m(formula = cbind(Agrade, n - Agrade) ~ caffeine + I(caffeine/2), family = binomial, data = caffeine. df) Deviance Residuals: Min 1Q Median 3Q Max -1. 38859 -0.67591 -0.08634 0 . 69945 1. 31565 Coefficients : Estimate Std. Error z value Pr(>|z)) (Intercept) -3. 974e-01 3.021e-01 -1.315 0. 18836 caffeine 4. 600e-03 3.633e-03 1.266 0.20538 I (caffeine 2) -2.762e-05 9.257e-06 -2.984 0. 00285 * * Signif. codes: 0 '* * *' 0. 001 " * * ' 0.01 '*' 0.05 '.' 0.1 ''1 (Dispersion parameter for binomial family taken to be 1) Null deviance: 69.3577 on 10 degrees of freedom Residual deviance: 7.6639 on 8 degrees of freedom AIC: 46.909 Number of Fisher Scoring iterations: 5 [1] 0. 4669742