Probability from Two-Way Tables

Step 1: Finding the Group

Tap the cell that represents {{ g.rLabels[s1.targetR] }} AND {{ g.cLabels[s1.targetC] }}.

	{{ col }}	Total
{{ row }}	{{ g.matrix[r][c] }}	{{ g.rTotals[r] }}
Total	{{ tot }}	{{ g.grand }}

What is the probability a random student is a {{ g.rLabels[s2.targetR] }} AND prefers {{ g.cLabels[s2.targetC] }}?

drag_indicator Drag numbers from the table to build the fraction.

	{{ col }}	Total
{{ row }}	{{ g.matrix[r][c] }}	{{ g.rTotals[r] }}
Total	{{ tot }}	{{ g.grand }}

P({{ g.rLabels[s2.targetR].split(' ')[0] }} & {{ g.cLabels[s2.targetC].split(' ')[0] }}) =

Check your numbers!

Conditional probability restricts our view. GIVEN that a student is a {{ g.rLabels[s3.targetR] }}...

Tap the {{ g.rLabels[s3.targetR] }} row header to focus ONLY on them.

	{{ col }}	Total
{{ row }}	{{ g.matrix[r][c] }}	{{ g.rTotals[r] }}
Total	{{ tot }}	{{ g.grand }}

GIVEN they are {{ g.rLabels[s4.condR] }}, what is the probability they prefer {{ g.cLabels[s4.targetC] }}?

Drag numbers from the highlighted row to build the fraction.

	{{ col }}	Total
{{ row }}	{{ g.matrix[r][c] }}	{{ g.rTotals[r] }}

P({{ g.cLabels[s4.targetC].split(' ')[0] }} | {{ g.rLabels[s4.condR].split(' ')[0] }}) =

Check your numbers! (Denominator should be the row total)

🏆

You successfully navigated two-way tables to find both joint and conditional probabilities!

Remember:

AND means the intersection out of the Grand Total.
GIVEN means you restrict the table to just one row or column, and use its Total.