Sample surveys on sensitive issues can give different results depending on how the question is asked. A University of Wisconsin study divided 2400 respondents into 3 groups at random. All were asked if they had ever used cocaine. One group of 800 was interviewed by phone; 167 said they had used cocaine. Another 800 people were asked the question in a oneonone personal interview; 190 said "Yes." The remaining 800 were allowed to make an anonymous written response; 224 said "Yes." Are there statistically signicant differences among these proportions? Carry out a chi-square test for association between interview type and response. Test H0 : the proportion of people who admit cocaine use is the same for all three interview methods versus H,z : the proportions are not the same (interview type makes a difference). Use a = 0.01. 12 (10.0001) = P (10.0001) =C 0 There is evidence that interview type makes a difference C There is no evidence that interview type makes a difference