Basic Marketing Research 8th Edition by Tom Brown,Tracy Suter,Gilbert Churchill

Exercise 18

An executive recruitment firm used a lengthy online survey to gather information on the job mobility of mid-level managers. A sample of 500 eligible middle managers was selected, using a simple random sampling procedure. The firm used three waves of recruitment e-mails. Sixteen of the questionnaires were returned due to incorrect e-mail addresses; all but two of the completed surveys were usable. After the third round of recruiting messages each of the nonresponding (NR) sample units was contacted by phone and asked to answer only four questions regarding variables that the recruitment firm thought were particularly important, given the objective of the study. The table below gives mean values for these variables.
a. What was the response rate for the completed questionnaire
b. Which variables, if any, seem to be most affected by potential nonresponse bias Does this tell you anything about the sample selection procedure