1 / 7

Chi-square Day 2

Chi-square Day 2. Student Edition. HW 1-Due Tuesday Due to Senior Ball and NMSI SSS.

jeb
Download Presentation

Chi-square Day 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chi-square Day 2 Student Edition

  2. HW 1-Due Tuesday Due to Senior Ball and NMSI SSS • The accuracy of a census in a city in southern California was questioned by congressional officials. A random sample was used to check the results and the data on the next slide was given to Congress. Test that the Census distribution agrees with the sample distribution.

  3. Practice Due Tuesday (Note: Not Chi-square) • Microsoft claims in an article that 75% of XBOX Live users buy add-ons for games while only 67% of PSN users buy game add-ons. In a study of 500 randomly selected XBOX Live users, 360 buy add-ons. In the same study, 75 out of 100 randomly selected PSN users bought add-ons Is there significant evidence that the proportion of gamers buying add-ons is greater for XBOX Live than PSN?

  4. Solution • Parameter 1: The proportion of XBOX Live users who buy add-ons for games • Parameter 2: The proportion of PSN users who buy add-ons for games. • Ho: p1 = p2 • Ha: p1 > p2 • Assumptions (SRS and Independence): The XBOX Live users and PSN users were stated to be randomly selected. It is unlikely either group affected each other or that individuals within each group affected each other’s add-on purchases, so independence can be assumed. It is also likely that each population is at least 10 times the sample size.

  5. Normality (corrected) • pc = (360 + 75)/(500+100) = .725 • n1pc= 500 (.725)= 362.5 • n1(1-pc) = 500 (1-.725) = 137.5 • n2pc= 100 (.725) = 72.5 • n2(1-pc) = 100 (1-.725) = 27.5 • All calculations are at least 10, so we can assume that the data are approximately normal.

  6. This is a 2-proportion z-test • Show work (not on this slide) • z = -.613 • p-value = .730 • At the α = .05 significance level, fail to reject Ho • There is no evidence to suggest that XBOX Live users buy more game add-ons than PSN users

More Related