Question 7
33 pts
Suppose you have a company offering a subscription service and would like to identify what
drives customer loyalty. To that end, you collect data on a large set of customers and run a
logistic regression where the response is Loyal which equals 1 if the customer has stayed with
your company for more than a year and O otherwise. As predictors, you use Age, Income, and
Single. Here, Age is the age of the customer, Income is income in $1000s, and Single is a
binary that is 1 if the customer is on a single plan and O otherwise. Below you see a
screenshot of the coefficients table of the summary output. Answer the questions below
based on this output. In your answers, instead of ex you may just type exp(x) whenever it
applies.
Coefficients:
Estimate Std. Error z value
(Intercept) -4.926652
Pr(>|z|)
0.863719
-5.704 0.00000001170302 ***
Age
Income
Single
0.036994
0.011378
3.251
0.00115 **
0.04322
0.006124
7.139 0.00000000000094 ***
-0.859315
0.380345
-2.259
0.02386 *
a) [6 points] Which predictors are significant at a confidence level of 95%? Explain your
reasoning.
b) [9 points] Predict the probability of being loyal for a 40-year-old customer, with an Income
of $80K and on a single plan.
c) [12 points] Compute and interpret the exact partial effect of each predictor on customer
loyalty odds when each predictor variable is increased by one unit while holding others
constant.
d) [6 points] Suppose we would like to see if we can improve this logistic regression by
including a new predictor. What performance measure can we use to compare the two
regressions? How would we know which logistic regression model is better? Why?