Sampling Methods: Identify the sampling method used and indicate why it will or will not give a representative sample.
(a) To determine the prevalence of human growth hormone (HGH) use among high school varsity baseball players, the State Athletic Commission randomly selects 50 high schools. A random sample of the selected high schools' varsity baseball teams are tested for HGH.
(b) To determine his DSL Internet connection speed, Shawn divides up the day into four parts: morning, midday, evening, and late night. He then measures his Internet connection speed each time he uses the internet in the morning.
(c) A survey regarding download time on a certain website is administered on the internet by a market research firm to anyone who would like to take it.
(d) A 24 Hour Fitness wants to administer a satisfaction survey to its current members. Using its membership roster, the club splits the day into morning, afternoon and night. Then randomly selects 40 club members from each time period and asks them about their level of satisfaction with the club.

Simple random sample
Stratified sample
Cluster sample
Convenience sample
Only using these sample