1. Location and Party affiliation
Warm – Up
Location and Party affiliation
Democrat Republican Independent
West
Northeast
Southeast 68 57 77
33.7%
28.2%
38.1%
202
1. Calculate the Marginal Distributions.
2. Calculate the Marginal Distribution Percentages for each location.

2. Conditional Distributions:
Ch. 3
Conditional Distributions:
A conditional distribution shows the distribution of one variable for just the individuals who satisfy some condition on another variable.

3. Example 1.
Democrat Republican Independent
West
Northeast
Southeast
46.4%
17.9%
35.7%
21.8%
38.5%
39.7% 68 57 77
202
1. Calculate the Conditional Distribution Percents for each of the three locations among the Democrats.
2. Calculate the Conditional Distribution Percents for each of the locations among the Republicans.

4. Democrat Republican Independent
West
Northeast
Southeast
57.4% % % 68 57 77
39.0% % % %
202
3. What is the Conditional Distribution of political affiliation for people living in the Southeast?
4. What is the Conditional Distribution of political affiliation for people living in the West?
5. Does there appear to be a relationship between location and party affiliation?

5. Two variables are considered independent (Not Associated) if the relative distribution of one level is approximately the same compared to the other levels.
If the relative distributions vastly differ, the variables are associated, meaning that they are not independent.

6. TITANIC Example 2. What % of the ship Survived? Died?
MARGINAL DISTRIBUTIONS PERCENTAGES:
What % of the ship Survived? Died?
What % of the ship was represented by First Class? Third Class?
32.3%
67.7%
14.8%
32.1%

7. 1. Find the conditional distribution % of Class, among the survivors:
32.3% Survived
67.7% Died
1. Find the conditional distribution % of Class, among the survivors:
2. Find the conditional distribution % of Class, among the dead.

8. In Conclusion…
We see that the distribution of Class for the survivors is different from that of the nonsurvivors… so “Class” did affect “Survival” on the Titanic. = Not independent

9. Homework Page 38: #18, 20-23 59.9%, are male.
14.1%, are “Conservative”.
18.3%, are “Conservative”.
10.9%, are
“Conservative”.
45.5%, are “Liberals”.
43.5%, are
“Liberals”.

10. Males: 43.5% Liberal, 38.3% Moderate, and 18.3% Conservative.
Females: % Liberal, 46.8% Moderate, and 7.8% Conservative.
The relative distribution differs among males and females so Politics and sex are NOT independent..