Critique the following methods of data collection.

a. A shopping mall places interviewers in the parking lot every Saturday to ask respondents where they live and the two to three stores they came to visit on this shopping trip.

b. To evaluate the popularity of a new television series, the broadcasting company invited people to install an app, provide name, gender and age, home address, e-mail address, and phone number, and to vote yes, they would watch it again, or no, they would not watch it again.

c. A supermarket recently completed a major renovation. To obtain customer reactions, the checkout personnel placed a short questionnaire into each customer’s grocery bag while putting the groceries in.