Regression

Inria

Abstract

In this tutorial, you will perform a logistic regression with R. This is the first exercice and we will do it together in class. At the end you can find an exercice with a simple linear regression you should be able to do alone at home (solutions will be given in next class).

Logistic regression application: credit default

The aim is to predict whether a client will have a credit card default from a few simple covariates.

In the ISLR package, there is a dataset Default which measures for 10000 clients 4 variables: - default: a factor variable corresponding to the presence and the absence of default - student: a factor variable having value Yes for a student and No otherwise - balance: the average credit card balance at the end of the month - income : the customer income

Question 1: load data

Load the Default data set in the package ISLR. Can you describe the data? If you want to predict the credit default, what will be the outcome?

Solution 1

library(ISLR)
data(Default)
head(Default)

10000 observations, 4 columns, the outcome will be default (a binary covariate)

End of solution 1

Question 2: data exploration

Perform typical univariate and bivariate data exploration. Can you already observe a trend?

Solution 2

Here you can find several plots with sometimes strange color. It is to show you different parameters to tune and choose your favorite plots. But don’t forget you can find a lot of examples online.

library(ggplot2)

## Warning: package 'ggplot2' was built under R version 3.6.2

ggplot(Default, aes(x = income)) +
  geom_histogram(binwidth = 500, fill = "white", color = "darkorange") +
  theme_bw()

ggplot(Default, aes(x = default)) +
  geom_bar() +
  facet_grid(~student) +
  theme_dark()

ggplot(Default, aes(x = default, y = income)) +
  geom_violin() +
  theme_bw() +
  geom_jitter(alpha = 0.05)