In the following situations, decide whether you would use a personal interview, observation, mailed questionnaire or telephone interview. Give your reasons.
a) A survey of the residents of a new subdivision on why they happened to select that area in which to live. You also wish to secure some information about what they like and do not like about life in the subdivision.
b) A poll of students at Metro University on their preferences among three candidates who are running for president of the students' union.
c) A survey of 108 wholesale grocery companies, scattered throughout a country, on their personnel management policies.
d) A survey of financial officers of the Fortune 500 Corporations to learn their predictions for the economic outlook in their industries in the next year.