Exer 7.1 [E/E114]  

AGid

The R² statistic is the ratio of the variance of the fitted values to the variance of the response variable.

Using the kidsfeet data:

1. Find the variance of the response variable in the model width ~ sex + length + sex:length .
   
    0.053  0.119  0.183  0.260  0.346  
   
2. Find the variance of the fitted values from the model
   
    0.053  0.119  0.183  0.260  0.346  
   
3. Compute the R² as the ratio of these two variances.
    0.20  0.29  0.46  0.53  0.75  
   
4. Is this the same as the “Multiple R²” given in the summary(mod) report?
    Yes  No