Hi I have a linear model and I want to tests whether the model terms are significant I used anova but F and P value depend on the order of the terms in the model. I have repeated the same analysis in another stat software and F and P value did not differ with order of terms in the model. Can anyone can explain what happen or what am I doing wrong ?
In R > anova (lm(Y~X.1+X.2)) Analysis of Variance Table Response: Y Df Sum Sq Mean Sq F value Pr(>F) X.1 1 4.0351 4.0351 6.5187 0.01852 X.2 1 0.5903 0.5903 0.9537 0.33991 Residuals 21 12.9991 0.619 > anova (lm(Y~X.2+X.1)) Analysis of Variance Table Response: Y Df Sum Sq Mean Sq F value Pr(>F) X.2 1 1.9651 1.9651 3.1747 0.08926 X.1 1 2.6603 2.6603 4.2977 0.05066 Residuals 21 12.9991 0.619 With another stat software (JMP) Y~X.1+X.2 Df Sum Sq Mean Sq F value Pr(>F) X.1 1 2.6603 2.6603 4.2977 0.05066 X.2 1 0.5903 0.5903 0.9537 0.33991 Residuals 21 12.9991 0.619 Y~X.2+X.1 Df Sum Sq Mean Sq F value Pr(>F) X.2 1 0.5903 0.5903 0.9537 0.33991 X.1 1 2.6603 2.6603 4.2977 0.05066 Residuals 21 12.9991 0.619 --------------------------------------------------------------------------- Julien Martin Canadian Research Chair in behavioural ecology Université du Québec à Montréal Email: [EMAIL PROTECTED] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html