TOK Question about Primary Research

Consider the following TOK question from the book (p. 378): “Given the complications of survey designs and sample size, can primary market research data ever be truly reliable?”
AND, consider: if secondary data is just someone else’s primary data (“data that already exists”), how do we know data is valid?
Find an article about market research (of any kind) that helps you answer this question.
Write a 250-500 word answer to these questions.