parcelles de diagnostic

layout(matrix(c(1,2,3,4),2,2)) # optional 4 graphs/page
plot(lm3)

#Looking at the Residual vs Fitted plot, I can say that there is some pattern 
#in how the residuals are spreaded, they are more frequent between 6 and 7 on fitted 
#residuals axis. Also, points on theleft seem to be too lonely. Normal Q-Q plot shows 
#that the fit to the normal distribution is not perfect, point follow the line, 
#but violate it on the ends. Looking at the Residuals vs Leverage plot, we conclude 
#that there can be few observation that stands out significantly (on the right side of 
#the plot), but they doent seem to affect the fit line strongly.
Diana H