Lecture 2

Question 1

When is a quantitative variable discrete?

Answer 1

If its possible values form a
set of separate numbers, such as 0,1,2,3

Question 2

When is a quantitative variable continuous?

Answer 2

if its possible values
form an interval

Question 3

What is a frequency table?

Answer 3

A listing of possible
values for a variable , together with the number of observations
and/ or relative frequencies for each value

Question 4

What is a pie chart used for?

Answer 4

summarizing a categorical variable

Question 5

How does a pie chart work?

Answer 5

Drawn as a circle where each category is represented as a “slice
of the pie”

• The size of each pie slice is proportional to the percentage of
  observations falling in that category

Question 6

Which is easier to compare categories?

Answer 6

A bar graph is usually easier for comparison to a pie chart.

Question 7

What is a bar graph used for?

Answer 7

Summarizing a categorical variable

Question 8

How do bar graphs work?

Answer 8

Bar Graphs display a vertical bar for each category
* The height of each bar represents either counts (“frequencies”) or
percentages (“relative frequencies”) for that category

Question 9

How do dot plots work?

Answer 9

Draw a horizontal line and Label it with the name of the variable

• Mark regular values of the variable on it
• For each observation, place a dot above its value on the number
  line