The Penn National Bank (PNB) has more than 500,000 users of credit cards throughout the state of Pennsylvania. In order to apply for a credit card, one must provide his/her name, address, phone number, income, and education. The bank is interested in determining whether there is a relationship between the way the card is used and the socioeconomic characteristics of the user. The PNB managers like to know if there is any difference between consumers who use the card for major purchases (e.g., appliances) and those who use it for minor ones. They also investigate whether the research design and techniques are appropriate in this case and why. 

Please answer the following questions

(a) What sampling frame the PNB should use? Why? 

(b) How would you draw a simple random sample from the sampling frame you suggested? 

(c) How would you draw a stratified sample from the sampling frame?

(d) Which method would you prefer? Why?