Large sample testfor a difference between

two proportions

Conditions

• Simple random Sample• Samples are Independent • Each sample point has just two possible

outcomes (success and failure)• Sample includes at least 10 successes and 10

failures(np>10 and nq>10 )

• Population size is at least 10 times larger than the sample

Conducting a Hypothesis test1- state the hypothesis: Ho & Ha (mutually exclusive)

*when the null hypothesis states there is no difference between the 2 population proportions (d=0), and it is a two tail test, then : Ho: P1=P2 & Ha: P1 = P2

2- Analysis Plan* Test Method: use a 2 proportion z-test to determine

whether the hypothesized differenced between the population proportions differs significantly from the observed sample difference

3- Analyze: find the TS and its associated P-value

** Standard Error:

**Pooled sample Proportion: (when P1=P2) then…

**both of these can be found in the table under two-sample

*P-value- probability of observing a sample statistic as extreme as the TS (where the TS is a z-score) (Use Appendix A )

4- Interpret- compare the P-value to the significance level and reject null when the P-value is less than the Significance level