Hi all, I try to test a linear slope using offset.
I have: > m2 <- glm(Y~X*V) > summary(m2) Call: glm(formula = Y ~ X * V) Deviance Residuals: Min 1Q Median 3Q Max -2.01688 -0.56028 0.05224 0.53213 3.60216 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 1.3673 0.8476 1.613 0.119788 X 4.0235 0.1366 29.453 < 2e-16 *** Vn2 0.9683 1.1987 0.808 0.427131 Vn3 4.6043 1.1987 3.841 0.000787 *** X:Vn2 4.1108 0.1932 21.279 < 2e-16 *** X:Vn3 -4.0069 0.1932 -20.740 < 2e-16 *** --- Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 (Dispersion parameter for gaussian family taken to be 1.53955) Null deviance: 15303.977 on 29 degrees of freedom Residual deviance: 36.949 on 24 degrees of freedom AIC: 105.39 Number of Fisher Scoring iterations: 2 It is clear that X slope is diferent of Zero. X 4.0235 0.1366 29.453 < 2e-16 *** It is too clear that X:Vn2's slope is diferent of X's slope and diferent of Zero, because is greater than X'slope. X:Vn2 4.1108 0.1932 21.279 < 2e-16 *** But, the X:Vn3' slope is different of X'slope, but not necessarily different of Zero. How I make to introduce this parameter in a new model for test? An offset only with Vn3 slope??? I try: m2 <- glm(Y~V*offset(0*X)) m2 <- glm(Y~X*V+V*offset(0*X)) m2 <- glm(Y~V:X+V*offset(0*X)) but neither work :(( Thanks for all. Ronaldo -- If you live in a country run by committee, be on the committee. -- Graham Summer -- | //|\\ [*****************************][*******************] || ( ő ő ) [Ronaldo Reis Júnior ][PentiumIII-600 ] | V [ESALQ/USP-Entomologia, CP-09 ][HD: 30 + 10 Gb ] || / l \ [13418-900 Piracicaba - SP ][RAM: 128 Mb ] | /(lin)\ [Fone: 19-429-4199 r.229 ][Video: SiS620-8Mb ] ||/(linux)\ [[EMAIL PROTECTED] ][Modem: Pctel-onboar] |/ (linux) \[ICQ#: 5692561 ][Kernel: 2.4.18 ] || ( x ) [*****************************][*******************] ||| _/ \_Powered by Gnu/Debian Woody D+:) | Lxuser#: 205366 ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help