Question

Astudent reporter receives approximately 400 responses. Nearly 86% said they were satisfied with the food, with a margin of error of 8%.

a) Why is this sample biased? Explain all reasoning.

b) What is the direction for the bias? Is the 86% probably higher or lower than the population parameter?

c) The researcher wants to lower the margin of error to 2%. How can she do this?

Answer 1

(a) This sample is biased because the sample bias is Response bias - Social Desirability. i.e., Since the survey results are not confidential, most of the students would like to report that they were satisfied with the food, even if their actual opinion is just the opposite because subsequently they may be troubled on some other pretext.

(b) The direction of the bias: 86 % is probably an over estimate.

The 86 % is probably higher than the population parameter.

(c) The researcher can lower the margin of error to 2 % by increasing the sample size from 400 to higher value.