lecture_8_1

# lecture_8_1 - Inference for proportions Significance test...

• Notes
• 6

This preview shows pages 1–6. Sign up to view the full content.

Inference for proportions Significance test for proportions IPS chapter 8.1 © 2006 W.H. Freeman and Company

This preview has intentionally blurred sections. Sign up to view the full version.

The sampling distribution of a sample proportion is approximately normal (normal approximation of a binomial distribution) when the sample size is large enough. p ˆ
Significance test for  p The sampling distribution for is approximately normal for large sample sizes and its shape depends solely on p and n . Thus, we can easily test the null hypothesis: z = ˆ p - p 0 p 0 (1 - p 0 ) n If H 0 is true, the sampling distribution is known The likelihood of our sample proportion given the null hypothesis depends on how far from p 0 our is in units of standard deviation. This is valid when both expected counts—expected successes np 0 and expected failures n (1 − p 0 )—are each 10 or larger. p 0 (1 - p 0 ) n p 0 ˆ p p ˆ p ˆ

This preview has intentionally blurred sections. Sign up to view the full version.

P-values and one or two sided hypotheses

This preview has intentionally blurred sections. Sign up to view the full version.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: — reminder And as always, if the p-value is smaller than (or equal to) the chosen significance level α , then the difference is statistically significant and we reject H . A national survey by the National Institute for Occupational Safety and Health on restaurant employees found that 75% said that work stress had a negative impact on their personal lives. You investigate a restaurant chain to see if the proportion of all their employees negatively affected by work stress differs from the national proportion p = 0 . 75. H : p = p = 0.75 vs. H a : p ≠ 0.75 (2 sided alternative) In your SRS of 100 employees, you find that 68 answered “Yes” when asked, “Does work stress have a negative impact on your personal life?” Is this result significant at the 5% level?...
View Full Document

• Spring '08
• ABDUS,S.
• Statistical hypothesis testing, 5%, 75%, National Institute for Occupational Safety and Health

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern