What is the “acceptable” margin of error in the 11 years of data collected by Nielsen using the dairy measurement? What are some of the problems of this methodology?

Read the attached article carefully. Answer the questions below:

Q1. What is the “acceptable” margin of error in the 11 years of data collected by Nielsen using the dairy measurement?

Q2. What are some of the problems of this methodology?

Q3. Nielsen saw a rise in accuracy of its ratings data after a change in their sampling strategy. What change did they make?

Q4. Why are non-responders a problem?