Methods to increase response rates to a population-based maternity survey: a comparison of two pilot studies

BACKGROUND: Surveys are established methods for collecting population data that are unavailable from other sources; however, response rates to surveys are declining. A number of methods have been identified to increase survey returns yet response rates remain low. This paper evaluates the impact of five selected methods on the response rate to pilot surveys, conducted prior to a large-scale National Maternity Survey in England. METHODS: The pilot national maternity surveys were cross-sectional population-based questionnaire surveys of women who were three months postpartum selected at random from birth registrations. Women received a postal questionnaire, which they could complete on paper, online or verbally over the telephone. An initial pilot survey was conducted (pilot 1, n = 1000) to which the response rate was lower than expected. Therefore, a further pilot survey was conducted (pilot 2, n = 2000) using additional selected methods with the specific aim of increasing the response rate. The additional selected methods used for all women in pilot 2 were: pre-notification, a shorter questionnaire, more personable survey materials, an additional reminder, and inclusion of quick response (QR) codes to enable faster access to the online version of the survey. To assess the impact of the selected methods, response rates to pilot surveys 1 and 2 were compared. RESULTS: The response rate increased significantly from 28.7% in pilot 1 to 33.1% in pilot 2 (+ 4.4%, 95%CI:0.88–7.83, p = 0.02). Analysis of weekly returns according to time from initial and reminder mail-outs suggests that this increase was largely due to the additional reminder. Most respondents completed the paper questionnaire rather than taking part online or over the telephone in both pilot surveys. However, the overall response to the online questionnaire almost doubled from 1.8% in pilot 1 to 3.5% in pilot 2, corresponding to an absolute difference of 1.7% (95%CI:0.45–2.81, p = 0.01), suggesting that QR codes might have facilitated online participation. CONCLUSIONS: Declining survey response rates may be ameliorated with the use of selected methods. Further studies should evaluate the effectiveness of each of these methods using randomised controlled trials and identify novel strategies for engaging populations in survey research. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12874-019-0702-3) contains supplementary material, which is available to authorized users.