Some say that the quantity of data that is collected is most important. Other say that the quality of the data is more important than the quantity. What is your opinion?

When formulating your answer it may be useful to come up with an example from your past experience where the quantity of data was not sufficient. Else, you can describe a case where the quality of the data was less than satisfactory. How did these deficiencies affected the validity of the conclusions of the analysis of the data?

For illustration consider the surveys. Conducting the survey by the telephone may be a fast way to reach a large number of responses. However, the quality of the response may be less that the response obtained by face-to-face interviews.