Lecture Ticket 4

Reading

Read the following sections of IFDAR.

• Chapter 4: sections 4.1 and 4.2 (Stop at 4.3 Factors)

Questions

1. What is a qualitative variable? What about a quantitative variable? How are they different?

2. What does the c() function do?

3. Suppose you have the following vector:

height_in <- c(70, 62, 72, 67)
height_in

[1] 70 62 72 67

What code would you write to replace the second element of height_in with the value 63?