Business Professor Thomas Callarman traveled to China more than a dozen times from 2000 to 2005. He warns people about believing everything they read about surveys conducted in China and gives two specific reasons: "First, things are changing so rapidly that what you hear today may not be true tomorrow. Second, the people who answer the surveys may tell you what they think you want to hear, rather than what they really believe" (T. E. Callarman, "Some Thoughts on China," Decision Line, March 2006, pp. 1, 43-44).
a. List the four types of survey error discussed in the paragraph above.
b. Which of the types of survey error in (a) are the basis for Professor Callarman's two reasons to question the surveys being conducted in China?