When comparing survey response rates for mail and online surveys, which one of the following statements is INCORRECT?
1) It is generally preferable to contact potential study participants by mail first.
2) There is no clear answer whether the response rate is higher for mailed or online surveys.
3) Any study comparing the mail vs web-based survey response rates would be limited to a specific target population and specific survey topic.
4) Multiple attempts to contact potential survey participants can be made using both methods.