A bank with branches in a large metropolitan area is considering opening its offices on Saturday, but it is uncertain whether customers will prefer (1) having walk in hours on Saturday or (2) having extended branch hours during the week. Several ideas for collecting data are listed below. Classify each scenario as one of the following sampling methods: Voluntary Response, Simple Random Sample, Convenience Sampling, Cluster Sampling, or Stratified Random Sampling. Also determine whether or not there is any bias associated with each scenario below.
1. Put an ad in the newspaper asking people to log their opinions on the bank's website.
2. Randomly select two of the branches and contact every customer at each of these banks by phone.
3. Randomly select 20 customers from each branch. Send each a survey, and follow up with a phone call if he or she does not return the survey within a week.
4. Sponsor a commercial during a TV program asking people to dial one of two phone numbers to indicate which option they prefer.
5. Go to a branch and talk with the first 200 customers who visits the branch that day.
6. Go through the bank's customer records and select 100 customers at random. Then hire a survey research company to interview them