1. Section 12.2 Two-Proportion z tests
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2. Comparing Two Proportions
Chapter 12 Section 2
Comparing Two Proportions
2-Proportion Z test – compares the proportion of successes in two independent populations by comparing the difference between the two population proportions, p1 and p2 .
(use identifying subscripts when labeling p)

3. Assumptions for 2 Prop. z Test: 2 independent SRSs N ≥ 10 n
Because we do not always know p1 or p2 the statistic that estimates this difference is the difference between the two sample proportions
Assumptions for 2 Prop. z Test:
2 independent SRSs
N ≥ 10 n
(n1)(p̂) ≥ 5 and (n1)(1-p̂) ≥ 5
(n2)(p̂) ≥ 5 and (n2)(1-p̂) ≥ 5

4. The 2-proportion Z test equation looks like: Z =
(everything below p̂1 - p̂2 is underneath the square root symbol)
Find Z value on table A and get corresponding
P-value.
P-value is interpreted the same as on the other
significance tests.

6. Assignment: p.688 & 689 #s 21 and 23