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Evaluating the Effectiveness of Two Strategies to Improve Telephone Survey Response Rates of Employers
*Jeremy Pickreign, NORC at the University of Chicago 
Heidi Whitmore, NORC at the University of Chicago 

Keywords: Incentives, personalized advance letter, response rate, telephone survey

The California Employer Health Benefits Survey sponsored by the California HealthCare Foundation has been hovering between 35 percent and 40 percent since 2004 with a 2010 response rate of 40 percent. The response rate in 2010 was 24 percent for non-panel firms and 27 percent for firms with 3-49 workers. This study examines two strategies for improving the response rate among these smallest non-panel firms via a telephone survey: 1) mailing a personalized advance letter and 2) offering financial incentives. We pre-called 1,024 non-panel firms with 3-49 workers for the 2011 survey and sent a personalized advance letter to 513 firms successfully contacted. Simultaneously, we randomly assigned these 1,024 firms to three incentive groups: firms sent a $20 incentive with the initial mailing; firms promised $20 upon completion of the survey; and a control group receiving no incentive. Results find that firms sent a personalized advance letter have a significantly higher response rate than those sent a generic advance letter (31.0 percent vs. 18.3 percent, p<0.001). Firms sent a financial incentive with the initial mailing (22.0 percent vs. 28.1 percent, p=0.209) or were promised $20 upon completion of the survey (30.0 percent vs. 28.1 percent, p=0.707) did not have significantly different response rates compared to firms receiving no incentives. This lack of significance is further supported via logistic regression analysis. Sending a personalized advance letter has a significant impact on improving the overall response rate while offering incentives does not.