[R] anova and lm results differ

[Iasonas Lamprianou]

Dear all
   
 I have found that the two "equivalent" commands do not produce the same results.
    1. (I wrote this command by hand, this is what I would do usually)
    >summary(aov(eduyrs ~ cntry * edf, data=ESS1))
                  Df Sum Sq Mean Sq  F value    Pr(>F)   
    cntry          1    257  256.65  21.2251 4.243e-06 ***
    edf            4  11010 2752.42 227.6296 < 2.2e-16 ***
    cntry:edf      4     24    6.03   0.4987    0.7367   
    Residuals   3205  38754   12.09                       
    ---
    Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
   
 2. (I run this from Rcmdr, this is what my students would normally do)
    >AnovaModel.2 <- (lm(eduyrs ~ cntry*edf, data=ESS1))
    > Anova(AnovaModel.2)
    Anova Table (Type II tests)
    Response: eduyrs
              Sum Sq   Df  F value  Pr(>F)   
    cntry         38    1   3.1158 0.07763 . 
    edf        11010    4 227.6296 < 2e-16 ***
    cntry:edf     24    4   0.4987 0.73672   
    Residuals  38754 3205                     
    ---
    Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
   
    Unfortunately, the results are different. Could anyone, please, explain why?
    

Dr. Iasonas Lamprianou


Assistant Professor (Educational Research and Evaluation)
Department of Education Sciences
European University-Cyprus
P.O. Box 22006
1516 Nicosia
Cyprus 
Tel.: +357-22-713178
Fax: +357-22-590539


Honorary Research Fellow
Department of Education
The University of Manchester
Oxford Road, Manchester M13 9PL, UK
Tel. 0044  161 275 3485
iasonas.lamprianou at manchester.ac.uk