Two-Way Tables and Association

Turn each row into a percentage, then Check yes or no: are the two things associated? Say why.

ExampleA survey asked students two questions.

	Has a job	No job	Total
Plays a sport	43	14	57
Does not play	25	45	70

For each row, work out the percentage who answered "Has a job". Does the table suggest the two things are associated? Explain.

Plays a sport: 75 % Does not play: 36 %

Associated? yesno

Why? the two percentages are far apart, so the answers do appear to be associated — knowing one makes the other more predictable; comparing percentages rather than raw counts matters, because the two rows have different totals

1.A survey asked students two questions.
Has a job No job Total
Plays a sport 49 21 70
Does not play 17 44 61
For each row, work out the percentage who answered "Has a job". Does the table suggest the two things are associated? Explain.
Plays a sport: % Does not play: %
Associated? yesno
Why?
2.A survey asked students two questions.
On time Late Total
Walks to school 37 20 57
Takes the bus 14 48 62
For each row, work out the percentage who answered "On time". Does the table suggest the two things are associated? Explain.
Walks to school: % Takes the bus: %
Associated? yesno
Why?
3.A survey asked students two questions.
Alert Not alert Total
Eats breakfast 22 24 46
Skips breakfast 24 27 51
For each row, work out the percentage who answered "Alert". Does the table suggest the two things are associated? Explain.
Eats breakfast: % Skips breakfast: %
Associated? yesno
Why?
4.A survey asked students two questions.
Wants one Does not Total
Owns a pet 31 30 61
No pet 38 31 69
For each row, work out the percentage who answered "Wants one". Does the table suggest the two things are associated? Explain.
Owns a pet: % No pet: %
Associated? yesno
Why?
5.A survey asked students two questions.
Alert Not alert Total
Eats breakfast 31 14 45
Skips breakfast 10 41 51
For each row, work out the percentage who answered "Alert". Does the table suggest the two things are associated? Explain.
Eats breakfast: % Skips breakfast: %
Associated? yesno
Why?

	On time	Late	Total
Walks to school	37	20	57
Takes the bus	14	48	62

	Alert	Not alert	Total
Eats breakfast	22	24	46
Skips breakfast	24	27	51

	Wants one	Does not	Total
Owns a pet	31	30	61
No pet	38	31	69

	Alert	Not alert	Total
Eats breakfast	31	14	45
Skips breakfast	10	41	51