Evaluation Briefs
No. 21 | July 2010

Increasing Questionnaire Response Rates

This brief describes the importance of boosting questionnaire response rates to increase the validity and usefulness of your results. It includes an explanation of what response rate is; strategies to increase response rates; special considerations for Internet questionnaires; and additional strategies to boost response rates.

Definition of response rate
In the simplest sense, response rate is the number of participants who completed a questionnaire divided by the total number of participants who were asked to participate. However, calculating response rates can be more complex depending on the design of your evaluation. Failure to achieve an adequate response rate can limit the usefulness of your results. The determination of what constitutes an adequate response rate should be based on the evaluation design, how the results will be used, and standard practice.

Strategies to increase response rates for mailed or faxed questionnaires
There are a variety of strategies that can help you motivate people to complete and return mailed or faxed questionnaires.
Personalize all mailings by Using agency letterhead on high quality paper. Signing cover letters individually in blue ink. Using recognizable graphics or logos on the questionnaire, letters, and envelopes. Handwriting addresses on mailing and return envelopes. Personalizing the mailing address on the envelope and the salutation in a cover letter rather than using a generic approach (i.e., Dear Colleague….). Avoiding traditionally busy periods such as holidays, districtwide testing days, and summer breaks when sending questionnaires to participants who work in schools or school districts.
Contact potential participants four times by Sending a personalized prenotification letter or postcard one week prior to mailing the questionnaire asking people to participate. You should indicate when they will receive the questionnaire and explain its purpose. Sending the questionnaire along with a cover letter and hand-addressed postage-paid return envelope by first-class mail. Like the prenotification letter, the cover letter should explain the importance of the questionnaire, state that responses are confidential (if they are), explain how the results will be used, and who should answer the questions. Sending a reminder postcard by first-class mail one week after mailing the questionnaire to thank participants for their response or to encourage them to respond if they have not already done so. Sending a replacement questionnaire to participants who have not responded (with a dated follow-up letter and a hand-addressed postage-paid return envelope) about three weeks after the initial questionnaire mailing.
Create a participant-friendly questionnaire by Limiting the number of questions to what you really need to know and asking only about topics that are relevant to the participants (see Evaluation Brief 15: Checklist to Evaluate the Quality of Questions). Providing clear and easy-to-follow instructions that make the questionnaire simple to complete. Using clear and simple language at or below the reading level of your participants. Avoid using abbreviations and technicaljargon (see Evaluation Brief 14: Data Collection
Methods for Program Evaluation: Questionnaires). Ending the questionnaire with a “thank you” and restating the due date and how to return the questionnaire. Folding the questionnaire forms into a booklet, rather than stapling the pages together. Using lightly shaded background colors, preferably light blue or green with white answer spaces to help participants quickly and clearly determine where to write their answers. Providing adequate space for participants to answer each question completely.

Special considerations for Internet questionnaires
You can increase response rates to Internet questionnaires using several techniques similar to those used for mailed or faxed questionnaires, such as designing user-friendly electronic questionnaires and making follow-up contacts with participants.
You may choose to eliminate the prenotification letter and start directly with the invitation e-mail, reducing the total number of contacts to three- an initial e-mail invitation to complete the questionnaire with an active and direct hyperlink to the questionnaire, and two follow-up e-mails. You should personalize your contacts by e-mailing each participant an individually addressed message. Keep all e-mail contacts short and to the point.

Additional strategies to boost response rates
Offer an incentive to encourage participants to complete the questionnaire (see Evaluation Brief 22: Using Incentives to Boost Response Rates). This could be a cash incentive, a gift card, or a nonmonetary gift. Telephone participants directly if they have not responded to the second questionnaire. Politely ask them if they have questions and whether they need help with completing the questionnaire. You may also consider completing the questionnaire as an interview by phone.

Resources
Boyd HH, How to Get a Respectable Response Rate. Madison, WI: University of Wisconsin-Extension; 2002. Available at http://www.uwex.edu/ces/pdande/resources/quicktipsnumerical.html
Brief 14: Data Collection Methods for Program Evaluation: Questionnaires. Available at http://www.cdc.gov/HealthyYouth/evaluation/pdf/brief14.pdf.
Brief 15: Checklist to Evaluate the Quality of Questions. Available at http://www.cdc.gov/HealthyYouth/evaluation/pdf/brief15.pdf.
Brief 22: Using Incentives to Boost Response Rates. Available at http://www.cdc.gov/HealthyYouth/evaluation/pdf/brief22.pdf.
Dillman DA, Smyth J, Christian L. Internet, Mail, and Mixed-Mode Surveys: The Tailored Design Method. 3rd Edition. Hoboken, NJ: John Wiley & Sons, Inc; 2009.
Edwards P, Roberts I, Clarke M, DiGuisepi C, Pratap S, Wentz R, et al. Increasing response rates to postal questionnaires: systematic review. British Medical Journal 2002;324(7347):1183–1185. Available at http://www.bmj.com/cgi/reprint/324/7347/1183.

For further information or assistance, contact the Evaluation Research Team at ert@cdc.gov.  You can also contact us via our website: http://www.cdc.gov/healthyyouth/evaluation/index.htm.