1. Two-way tables can be used to examine relationships between two
Suppose we have data on 200 students regarding their gender and whether or not they wear backpacks to school. The data is summarized in the two-way table below. 2. Fill in the remaining numbers in the table.
Different ways to summarize the data from a two way table
3. A _______ distribution summarizes the data from one variable only.
4. Find the marginal distribution of gender:
6. Find the marginal distribution of backpack use:
8. Note: the sum of all the percentages in a marginal distribution equals ____.
Graphing a marginal distribution:
9. Graphical versions of a marginal distribution can be done using a _________ or a __________ showing the percentage in each group.
10. Graph the marginal distribution of gender using a pie chart:
11. Graph the marginal distribution of backpack use using a bar graph:
How do we look for relationships between two categorical variables? 12. Big Idea: Break down the data into groups and compare the results of each group. This involves finding a ___________distribution.
13. To look for relationships between two variables you can find the two ______________ distributions and ___________ them to each other.
14. If the results of each group are the same, then the two variables are / are not related. (pick one).
15. Find the conditional distribution of backpack use for the males:
16. **Another way of describing the above distribution is to say this is the conditional distribution of ____________ given __________.**
17. Interpretation of the previous graph:
18. Find the conditional distribution of backpack use given female:
Making the comparisons:
20. You can look for relationships between two variables by comparing their __________distributions.
21. Using the above conditional distributions, is there is a relationship between gender and backpack use for the students in the sample?
22. Justify your YES or NO answer:
23. If there IS a relationship, describe the relationship using percentages in a sentence or two. Comparing Conditional Distributions using Graphs
24. Graphing 2 conditional distributions can be done using two __________, or two __________; or one stacked bar graph.
25. Graph the conditional distributions of backpack use for 1) the males and 2) the females using two bar graphs.
Gender and # friends on Facebook
Everyone is studying how people are using the social media. Below are the results of one large study of Facebook users; they studied gender (male, female, and unspecified) and number of friends (1, 2-25, 25-60, …, 10,000+), for all those users who have at least one friend. Use this data to answer the questions below the data set. IMPORTANT NOTES:
Gender has 3 categories: 1) male; 2) female; and 3) unspecified. We assume all Facebook users in this study have at least one friend. At least one friend = Those with 1 friend + Those with more than 1 friend Grand totals for those with at least one friend are at the very bottom of the data table.
# Friends and Gender
Women that have only 1 friend
Men that have only 1 friend
Unspecified gender that have only 1 friend
Total number that have only 1 friend
Women that have 2-25 friends
Men that have 2-25 friends
Unspecified gender that have 2-25 friends
Total number that have 2-25 friends
Women that have 26-50 friends
Men that have 26-50 friends
Unspecified gender that have 26-50 friends
Total number that have 26-50 friends
Women that have 51-100 friends
Men that have 51-100 friends
Unspecified gender that have 51-100 friends...
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