In a survey of homemakers, the readership of Harper’s Bazaar was exaggerated and the readership of Modern Romance seemed much less than circulation figures indicated. Why would respondents incorrectly report their readership in this manner?

This is basically a discussion giving feedback on these questions for marketing research class
This is the topic:
In a survey of homemakers, the readership of Harper’s Bazaar was exaggerated and the readership of Modern Romance seemed much less than circulation figures indicated. Why would respondents incorrectly report their readership in this manner?
How might researchers avoid this bias?
Are there other topics which might lead respondents to over- or under-represent their engagement? Such as? Why?
(As you develop your contributions to the discussion, be sure to include concrete examples and supporting evidence to help others understand your points.)