1. Lesson 2
9/4/12

2. Do Now: Represent this data graphically
9/4/12
Lesson 2
Do Now:
Represent this data graphically
Siblings
Erika 1
Samuel 2
Ryan
Nicky
Tia
Pop. Home Town
Erika
1,200,000
Samuel
5,000
Ryan
Nicky
20,000,000
Tia
8,000

3. Homework: Read chapters 2 and 3 Answer CIRCLED questions on hand-out:
They are on pg of book, #6,8,13,18,22,24

4. Frequency Table
Name
Pairs of Shoes
Sam 4
Erika 16
Tia 12
Ryan 6
Nicky 21
A Frequency Table organizes counts (data) by providing totals and category names.
A bar chart displays the distribution of a categorical variable, showing the counts for each category next to each other for easy comparison

5. Relative Frequency Table
Name
Pairs of Shoes
% Total Shoes
Sam 4
6.78%
Erika 16
27.12%
Tia 12
20.34%
Ryan 6
10.17%
Nicky 21
35.59%
Name
Pairs of Shoes
Sam 4
Erika 16
Tia 12
Ryan 6
Nicky 21
A relative frequency table displays the percentages, rather than the counts, of the values in each category.

6. Pie Charts Titanic Passengers
Pie charts show the whole group of cases as a circle
How easy is it to tell there are almost twice as many third-class passengers as first class passengers?

7. Comparing Displays
Titanic Passengers

8. Categorical Data Condition
Data must be counts or percentages of individual categories
No Overlap!

9. Area Principle
The area occupied by a part of the graph should correspond to the magnitude of the value it represents

10. Contingency Table
Right Handed
Left Handed
Totals
Males 43 9 52
Females 44 4 48 87 13
100
In order to look at two categorical variables together we often arrange counts in a two-way table.
The margins of a contingency table hold the frequency distributions for the data, for each variable this is called the marginal distribution
Right Handed
Left Handed
Totals
Males
43% 9%
52%
Females
44% 4%
48%
87%
13%
100%

11. Conditional Distributions
If we look at each row separately we can see the distribution of left/right handedness under the condition of gender
These percentages are called Conditional Distributions Why?
Right Handed
Left Handed
Totals
Males 43 9 52
82.69%
17.31%
100%
Females 44 4 48
91.67%
8.33%

12. Conditional Distributions (Cont.)
We can turn our conditional distribution around and look at gender for each type of handedness.
What is the new “Who”?
Right Handed
Left Handed
Totals
Males 43 9 52
49.43%
69.23%
52%
Females 44 4 48
50.57%
30.77%
48% 87 13
100
100%

13. Conditional Distributions
Is your handedness dependent on your gender?
Probably not.
These two variables appear to be independent.

14. Segmented Bar Chart

15. Fin
HW: Handout