10.20 Blue jay morphology: Sex and size. The dataset in the file

BlueJays includes Head (head length, in mm) and Mass (in gm) for

a sample of blue jays. We want to study the relationship between

sex (coded as M/F in the variable KnownSex and as 1/0 in the

variable Sex) and these measurements.

a. Make parallel boxplots of Head by KnownSex and Mass by KnownSex. Which of these two predictors has the strongest

relationship with KnownSex?

b. Fit a simple logistic regression model on Sex depending on

Mass. What is the P-value for testing that Mass has no

predictive power?

c. Fit a multiple logistic regression model of Sex depending

on Mass and Head. Which is the P-value for the coefficient

of Mass in the multiple logistic model?