Increasing Response Rates in a Survey of Medicaid Enrollees

Abstract

We sought to evaluate the effect of pairing a mixed-mode mail and telephone methodology with a prepaid US 2.00 dollars cash incentive on response rates in a survey of Medicaid enrollees stratified by race and ethnicity. Sampling was conducted in 2 stages. The first stage consisted of a simple random sample (SRS) of Medicaid enrollees. In the second stage, American Indian, African American, Latino, Hmong, and Somali enrollees were randomly sampled. A total of 8412 enrollees were assigned randomly to receive a mail survey with no incentive or a US 2.00 dollars bill. The response rate within the SRS after the mail portion was 54% in the incentive group and 45% in the nonincentive group. Response rates increased considerably with telephone follow-ups. The incentive SRS response rate increased to 69%, and the nonincentive response rate increased to 64%. Differences between incentive conditions are more pronounced after the first mailing (P < 0.01); almost all differences remained significant (P < 0.05) after the completion of the mail mode. The inclusion of the US 2.00 dollars incentive had similar effects on response rates and cost across the different racial and ethnic strata, except for Latino enrollees. A mixed-mode mail and telephone methodology is effective for increasing response rates in a Medicaid population overall and within different racial and ethnic groupings. The effectiveness of this strategy can be enhanced, in terms of response rate and cost, by including a US 2.00 dollars prepaid incentive.