Question :
In a sample of 600 men from a certain large city , 450 are found to be smokers. In another sample 900 from other large city, 650 are smokers. Do the data indicate that the cities are significantly different with respect to the prevalence of smoking among men?
Look at your notes and/or text for testing the difference of two proportions.
Or google finds:
http://stattrek.com/AP-Statistics-4/...px?Tutorial=AP
despite what looks like a type in this it still looks a nice explanation:
http://www.pinkmonkey.com/studyguide...8/s0808f01.asp
CB
The question does not provide you with a level of significance or a level of confidence. My intro textbook always provides this information in such a question. Since "significantly different" is used in the question, you probably should try the significance level approach. There are two significance levels used in my textbook, 1% and 5%. Choose the level which results in the most powerful test. Do you know which percentage gives your test the most power? Read your textbook or go to CaptainBlack's links. Spoonfeeding you the answer is not good for your learning curve.
The basic idea is that as the sample sizes are large and the probabilities are in the suitable range we can assume that the sampling distributions of the two proportions are normal with standard deviations . Now the z-score arises when we construct a test under these assumptions as a test statistic with a standard normal distribution that we can use to look up in a table.
CB
My work Please let me know if it is correct or no
Formulate the Analysis Plan :
-Significant level : 0.05
-Test Method
Analysis of Sampled data
Pooled Sampled proportion: =0.7
: sampled proportion
: sampled proportion
: size of 1st sample
: size of 1st sample
Standard Error (SE) = = 0.025
Test Statistic (z) = = 1.2
z<-1.2=: 0.11507
Is this correct??????