Consider the sampling designs provided below. For each sampling design, indicate whether or not the sampling is flawed. If the sampling is flawed, point out the type of error that is being made. In addition, if the sampling design is flawed suggest a method of correcting it and generating a satisfactory sampling design to answer the question being asked.
a) An anti-gun advocate wants to estimate the percentage of people who favor stricter gun laws. He conducts a nationwide survey of 1203 randomly selected adults 18 years old and older. The interviewer asked the respondents, "Do you favor harsher penalties for individuals who sell guns illegally?"
b) A produce buyer for supermarket is inspecting crates of peaches. He examines 20 peaches from the top of each crate and purchases a crate if all 20 peaches are satisfactory.
c) You are conducting a survey regarding illicit drug use among teenagers in Baltimore schools. You obtain a cluster sample of 12 schools within the district and sample all the sophomore students in the randomly selected schools. The survey is administered by the teachers.
d) A radio station asks its listeners to call in their opinions regarding the use of US forces in peacekeeping missions.
e) A farmer divides his orchard and 50 equal subsections, randomly selects 6 such sections, and samples all the trees within the 6 subsections to approximate the yield of his orchard.
f) Drexel University conducts student course evaluations online by requesting that students complete the online evaluations. All students who are in a particular course have access to the specific course evaluation for that class.