A1. What is a true experimental design? If the manager of McDonald wants to test whether the newly introduced new ice-cream with green tea-flavour can increase McDonalds sales, he conducts an experiment by asking consumers satisfaction and purchase intent with McDonald before and after the introduction of the new burger. After comparing the sales, the manager concludes that the newly introduced new burger of peach-flavour is successful because the sales increase substantially. Does his conclusion valid? If no, what is the problem? Please explain. (3 marks)

A2. Consumer preferences for Lovely shampoo were obtained on a 10-point Likert scale with 1 = least preferred and 10 = most preferred. The same consumers were asked to indicate preference of Lovely before and after watching a TV commercial about Lovely. The research wants to find whether the commercial has been successful in inducing a change in preference. What statistical analysis should be conducted? Please explain. (2 marks)

A3. Please determine the approximate sample size for a population with variability (P) of 30 percent, precision (allowable sample error) of 5%, and confidence level of 95%. Please illustrate and explain your calculation process step by step (2 marks). If a sample is drawn using the sample size formula and we find the sample percent is 50%, what would be the range of the true population percent? Please explain. (2 marks)

A4. The Library of HKU is conducting a survey to understand if its users have experienced any loss of properties in the Library and their opinions to improve the Librarys safety. The three alternative sampling methods are: a. A random page of the list of Library card numbers would be selected, a random number on that page would be selected, and the name corresponding to this number would be contacted. The same procedure would be repeated until 500 Library users are identified. b. Start at a random Library card number, and select every 20th number on the list of Library users. Contact all the card owners selected. c. Ask each Department Head of HKU to recommend 10 students. Contact these students individually to complete the survey. Identify the sampling method being proposed in each case and their strengths with reference to the situation of HKU Library. (3 marks)