Please answer questions 5b with 6.

56.. The manager of a shopping center recently conducted a survey to provide information on the types of stores that should be sought for the center's new wing, which was under construction. The questionnaires were distributed by placing them on tables near the entrances to the center. A large sign above each table said: "Help Us Plan the New Wing." Deposit boxes for completed questionnaires were provided at each table. The tables were left up for a two-week period. What type of errors are likely to be present in this study? What changes, if any, would you suggest? 6. Theater tests of advertising effectiveness sometimes involve having several groups of people observe a pilot film for a television series which has a number of commercials interspersed. Several groups see a commercial for the brand under test whereas other groups do not see this commercial. After the showing, the viewers complete a questionnaire which, in part, measures their attitude toward the test brand. Differences in attitudes between those who saw the commercial and those who did not are a measure of the commercial's effectiveness. What type of experiment is this? What type of errors are likely to affect it? What changes, if any, would you suggest