Answer
a. No, it is a biased estimate of the current average annual income of all 5432 alumni, because many alumni do not respond to the questionnaire, therefore, a nonresponse bias will occurred.
b. Nonresponse bias is presented.
c. I expect the estimate of $61,200 to be above the current average annual income of all 5432 alumni, because the respondents are free to choose whether they want to return the questionnaire, hence there is an inclination that those who responded to the questionnaire tend to inform the salary higher than their actual annual income.
Work Step by Step
a. No, it is a biased estimate of the current average annual income of all 5432 alumni, because many alumni do not respond to the questionnaire, therefore, a nonresponse bias will occurred.
b. Nonresponse bias is presented.
c. I expect the estimate of $61,200 to be above the current average annual income of all 5432 alumni, because the respondents are free to choose whether they want to return the questionnaire, hence there is an inclination that those who responded to the questionnaire tend to inform the salary higher than their actual annual income.
