Discussion 3 Stats 572 Andre Vega

Import Data and create data frame

Question a)

Find the regression of y on x1. If you were unaware of the possible importance of x2, could you conclude that y is reasonably well explained by x1 alone?

#alternatively you can use:
abline(mod1, col = "red")

Error in int_abline(a = a, b = b, h = h, v = v, untf = untf, ...) : 
  plot.new has not been called yet

Use plot(mod1) and follow the instructions in the console to get 4 diagnostic plots

Question b)

Repeat part (a) for the regression y on x2 (height)

Use plot(mod2) and follow the instructions in the console to get 4 plots that give information of the assumptions in the mod2

We can square root transform y in case we are not satisfied with our previous fit

Question c)

For the regression of y on x1 and x2, consider fitting the model in two ways (i) x1 enters the model first and then x2; (ii) x2 enters the model first and then x1. Compare the two ANOVA tables that R produces.

summary(aov_2)

            Df Sum Sq Mean Sq F value   Pr(>F)    
Diameter     1   2223    2223   169.6 1.22e-12 ***
Height       1   4658    4658   355.4 2.72e-16 ***
Residuals   25    328      13                     
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1