J. Hoffman was the owner of a medium-sized supermarket located in Phoenix, Arizona. He was considering altering the layout of the store so that the frozen food section would be near the section with fresh fruits and vegetables. These changes were designed to better accommodate customer shopping patterns and thereby increase customer patronage. Prior to making the alterations, he decided to administer a short questionnaire in the store to a random sample of customers. For a period of two weeks, three of the store cashiers were instructed to stand at the end of selected aisles and conduct personal interviews with every fifth customer. Hoffman gave specific instructions that on no account were customers to be harassed or offended. Identify the major sources of noncoverage and nonresponse errors. Explain.