Response rate (survey)

In survey research, response rate, also known as completion rate or return rate, is the number of people who answered the survey divided by the number of people in the sample. It is usually expressed in the form of a percentage. The term is also used in direct marketing to refer to the number of people who responded to an offer.

The general consensus in academic surveys is to choose one of the six definitions summarized by the American Association for Public Opinion Research (AAPOR).^[1] These definitions are endorsed by the National Research Council and the Journal of the American Medical Association, among other well recognized institutions.^{[citation needed]} They are:

1. Response Rate 1 (RR1) – or the minimum response rate, is the number of complete interviews divided by the number of interviews (complete plus partial) plus the number of non-interviews (refusal and break-off plus non-contacts plus others) plus all cases of unknown eligibility (unknown if housing unit, plus unknown, other).
2. Response Rate 2 (RR2) – RR1 + counting partial interviews as respondents.
3. Response Rate 3 (RR3) – estimates what proportion of cases of unknown eligibility is actually eligible. Those respondents estimated to be ineligible are excluded from the denominator. The method of estimation *must* be explicitly stated with RR3.
4. Response Rate 4 (RR4) – allocates cases of unknown eligibility as in RR3, but also includes partial interviews as respondents as in RR2.
5. Response Rate 5 (RR5) – is either a special case of RR3 in that it assumes that there are no eligible cases among the cases of unknown eligibility or the rare case in which there are no cases of unknown eligibility. RR5 is only appropriate when it is valid to assume that none of the unknown cases are eligible ones, or when there are no unknown cases.
6. Response Rate 6 (RR6) – makes that same assumption as RR5 and also includes partial interviews as respondents. RR6 represents the maximum response rate.

The six AAPOR definitions vary with respect to whether or not the surveys are partially or entirely completed and how researchers deal with unknown nonrespondents. Definition #1, for example, does NOT include partially completed surveys in the numerator, while definition #2 does. Definitions 3–6 deal with the unknown eligibility of potential respondents who could not be contacted. For example, there is no answer at the doors of 10 houses you attempted to survey. Maybe 5 of those you already know house people who qualify for your survey based on neighbors telling you whom lived there, but the other 5 are completely unknown. Maybe the dwellers fit your target population, maybe they don't. This may or may not be considered in your response rate, depending on which definition you use.

Example: if 1,000 surveys were sent by mail, and 257 were successfully completed (entirely) and returned, then the response rate would be 25.7%.