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Warm-up 10.3 Chi-Square test of Independence

Warm-up 10.3 Chi-Square test of Independence. A senator’s approval rating stood at 76% before she took a crucial vote.

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Warm-up 10.3 Chi-Square test of Independence

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  1. Warm-up10.3 Chi-Square test of Independence A senator’s approval rating stood at 76% before she took a crucial vote. a. His staff believes the rating is still around 76%. To confirm this, how large of an SRS should they sample to obtain a 90% confidence interval estimate with a margin of error < 3%? b. His staff randomly samples 600 people and finds 440 people approve of the senator’s job performance. Is there evidence that the rating as changed from 76%? Perform the appropriate statistical test to determine the p-value. The null hypothesis is that the senator’s approval rating is 76%. The alternate hypothesis is that is that the senator’s approval rating is not 76%. Draw the distribution curve and be sure to show all the appropriate values to decide whether to reject or fail to reject the null hypothesis.

  2. 2nd Index card • Everyone stand. • If the statement doesn’t apply to you sit down. • After the second statement guess who it is.

  3. Χ2 Test of Independence is very similar the the Χ2 Test of Homogeneity, except you are looking at only two factors and the variations on those factors. Keywords: association, relationship or any words that lead you to believe they are asking you if one may influence the other. Χ2 Test of Independence Ho: __________ and ______ are independent. Ha: __________ and ______ are not idependent. Χ2 Test of Homogeneity Ho: __________, _______, (2 or more categories) etc.have the same distribution of ________. Ha: ________ , ________ (2 or more categories) etc. have the different distribution of _________ .

  4. First Example Problem: A study from the University of Texas Southwest Medical Center examined whether the risk of Hepatitis C was related to whether people had tattoos and where they got their tattoos.

  5. Calculate Expected Before Conditions % with Hep. C ___ % without Hep C ___ Step 1:

  6. Tattoo and Hepatitis Problem Continued… The conditions are somewhat met. I’ll use a chi-square model with 2 df and a chi-square test of independence. I will proceed with caution because of the two cells that do meet the expected cell frequency. Step 2: Step 3:

  7. Conclusion Step 4:The P-value is vey small, so I reject the null hypothesis and conclude that Hepatitis Status is not independent of Tattoo Status. Since Expected Cell Frequency condition was violated, I need to check the two cells will small expected counts did not influence the results too greatly.

  8. Complete #4 of Chi-Square Worksheet The following information displays the eye color and hair color of 5,387 Scottish children. You might suspect that people with darker hair color tend to also have darker eye colors, whereas people with lighter hair colors tend to have lighter eye colors. In this case is there an association between the two?

  9. % with blue eyes ____ % with light eyes ____ % with medium eyes ____ % with dark ___

  10. Ch. 10 Notebook Check Notes: 1) 10.1 2) 10.2 3) χ2 Worksheet 4) 10.3 20 pts each = 80 pts Definitions: 7 terms 2 pts each = 14 pts When you finish #4 of Chi-Square Worksheet Work on problems from 10.2 and 10.3. for homework. 10.2:E#18, show all 4 steps of the significance test 10.3: E#36, follow the directions for a. to c.

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