Question: Comment on the following sampling designs:

i. A PIBG, interested in generating public and financial support for a new school badminton hall has published a questionnaire in area (local) newspapers. Readers return the questionnaires by mail.

ii. A department store that wishes to examine whether it is losing or gaining customers draws a sample from its list of credit card holders by selecting every tenth name.

iii. A motorcycle manufacturer decided to research consumer characteristics by sending 100 questionnaires to each of its dealers. The dealers would then use their sales records to trace buyers of this brand of motorcycle and distribute the questionnaires to them.

iv. A research company obtains a sample for a focus group through organized groups such as clubs or schools. The organizations are paid for securing respondents, and no individual is directly compensated.

v. A banner ad on a business-oriented Web site reads, “Are you a large company Senior Executive? Qualified executives receive $50 for less than 10 minutes of time. Take the survey now!” Is this an appropriate way to select a sample of business executives?