Propensity score matching to measure the effect of survey mode on reports of racial and ethnic discrimination in health care

Objective: To examine the effect of survey mode (mail vs. telephone) on the likelihood of reporting health care-related discrimination based on race, ethnicity, or nationality. Methods: We use data from a mixed-mode, mail and telephone survey of public health care program enrollees (N=2807), including Somali, Hmong, African American, American Indian, and Latino populations. Self-reported discrimination was measured as the experience of unfair treatment by health care providers due to race, ethnicity, or nationality. We use propensity score matching to create exchangeable groups of phone and mail respondents based on the probability of completing the survey by phone. Results: Overall, 33.1% of respondents reported having experienced discrimination in health care, but only 23.6% of telephone respondents reported discrimination compared with 36.8% of mail respondents. After matching phone and mail respondents based on probability of responding by telephone, all observable significant differences between respondents that were brought about by differential self-selection into mode were erased, allowing us to estimate the effect of survey mode on report of discrimination. Even after matching, the mode effect remains, where report of health care discrimination for telephone respondents would have been 12.6 percentage points higher had they responded by mail (22.6% vs. 35.2%). Conclusions: Survey mode has a significant effect on report of discrimination. Respondents may be more willing to disclose experiences of discrimination in a mail survey than to a telephone interviewer. Findings have substantial policy and clinical significance as variation in report of discrimination based on mode may lead to underestimation of the extent of the problem.