Two-Way Tables and Association

Two categorical variables at once.

12 problems · about 21 minutes · TEKS P.S.2.E, S-CP.A.4

NameDate

Figure — use these to answer the problems

Two groups with different totals. Compare percentages rather than counts before claiming an association.

Group 1 yes30

Group 1 no20

Group 2 yes6

Group 2 no4

Group 1 yes30

Group 1 no20

Group 2 yes6

Group 2 no4

Figure 1

Straightforward practice. Get the method working first.

5 problems

A row has 18 yes out of 24. What proportion said yes, as a decimal?
Answer
2
Why compare percentages rather than counts across groups?
- The groups may be different sizes, making counts incomparable.
- Percentages are easier to read.
A row has 15 yes and 5 no. Proportion yes, as a decimal?
Answer
Cells 10, 10, 20, 20. Grand total?
Answer
Row 1 rate 0.6, row 2 rate 0.6. Is there association? 1 yes, 0 no.
Answer

The same ideas with more to keep track of.

3 problems

Row 1 rate 0.8, row 2 rate 0.3. Is there association? 1 yes, 0 no.
Answer
A row has 9 yes out of 12. Proportion, as a decimal?
Answer
Where do marginal frequencies appear? 1 inner cells, 2 row and column totals.
Answer

Mixed problems. Work out what kind of question it is before you start.

4 problems

9
Match each term with where it lives in a two-way table.
Draw a line from each item on the left to its match on the right.
- Joint frequency
- Marginal frequency
- Conditional distribution
- An inner cell
- A row or column total
- A row divided by its own total
A row has 7 yes out of 28. Proportion, as a decimal?
Answer
The Row
A row has 30 yes and 20 no. What proportion said yes, as a decimal?
Answer
The Margin
Cells hold 12, 8, 5 and 15. What is the grand total?
Answer