The following data   are from an experiment designed to investigate the perception of corporate   ethical values among individuals specializing in marketing (higher scores   indicate higher ethical values).   Marketing Managers- 6,5,4,5,6,4   Marketing Research- 5,5,4,4,5,4   Advertising- 6,7,6,5,6,6   a) Use a=.05 to test for significant   differences in perception among the three groups.   b) At the a=.05 level of significance,   we can conclude that there are differences in the perceptions for marketing   managers, marketing research specialists, and advertising specialists. Use   the procedures in this section to determine where the differences occur. Use   a=.05.