Department

StatisticsCourse Code

STAB22H3Professor

ShristaLecture

4This

**preview**shows half of the first page. to view the full**2 pages of the document.**Statistics I

Lecture 4: Quantitative Data: How to display and summarize

Review

●Why need to display data?

●Different ways of displaying Categorical Data? - Bar Chart, Pie Chart,

Contingency Table

●Contingency Table review

Recall

Quantitative data - It can be measured (with units), i.e., it takes numerical values.

Since, we don’t have any categories in quantitative data, the method of displaying its

distribution differs from that of categorical data.

Displaying Quantitative

There are different ways to display the distribution of quantitative data:

1. Histogram

2. Stem - and - Leaf Plot / Display

3. Dotplots

Histogram

●Since, we don’t have categories in quantitative data, we divide the values into

equal - sized bins or classes

●Just like a bar chart, we have the vertical (y - axis) to be the frequency for the

data, i.e., the count / percent observations in classes

●What is the difference between a histogram and a bar chart?

Example

Page 79, Data from Q. 14.

Annual numbers of deaths from tornadoes in the United States from 1990 through 2000.

53 39 39 33 69 30 25 67 130 94 40

Let’s create a histogram!

Stem - and - leaf plot / display

●It is like a histogram, except, it shows the individual values in addition to the

shape of the data.

●How can we get this plot with the data given?

Example revisited

53 39 39 33 69 30 25 67 130 94 40

Again, first step - Sort the data to write them in ascending order.

25 30 33 39 39 40 53 67 69 94 130

Second step - Establish the leaf unit. In this case, leaf unit=1

Third step - Display data.

Example revisited

Stem - and - leaf plot

Leaf unit = 1 2 I 5

3 I 0 3 9 9

4 I 0

5 I 3

6 I 7 9

7 I

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