In the book Essentials of Marketing Research, William R. Dillon, Thomas J. Madden, and Neil H. Firtle (1993) present preexposure and postexposure attitude scores from an advertising study involving 10 respondents. The data for the experiment are given in Table 10.3. Assuming that the differences between pairs of postexposure and preexposure scores are normally distributed:
a. Set up the null and alternative hypotheses needed to attempt to establish that the advertisement increases the mean attitude score (that is, that the mean postexposure attitude score is higher than the mean preexposure attitude score).
b. Test the hypotheses you set up in part α at the .10, .05, .01, and .001 levels of significance. How much evidence is there that the advertisement increases the mean attitude score?
c. Estimate the minimum difference between the mean postexposure attitude score and the mean preexposure attitude score. Justify your answer.