In order for research to be most effective, the people included need to be as diverse as possible.  That is why the hundreds of papers each year that are surveys of psychology undergraduates who got extra credit come up with the kind of crazy conclusions mainstream media love to write about, but don't have the credibility of clinical trials.

In America, diversity in research is a struggle.  Black and female patients are less likely to agree to participate in research, despite being offered more frequent opportunities to participate. 

A new paper has found a new wrinkle. Black patients, both male and female, were 15 percent less likely to be willing to participate in research when approached by a white male study assistant, compared to white patients.  Are they racist? No, black patients were about 50 percent less likely to be willing to participate in research when approached by a black female study assistant, compared to white patients.  So are they sexist and racist? No, black patients were about 15 percent more likely to be willing when approached by a white female study assistant.

"Social theories about relationships between medical providers or researchers and patients suggest that patients may have more trust in providers who are similar to them in terms of gender and race, but there are few research studies that directly address race and sex differences between medical researchers and patient participants," says Kimberly Hart, a research associate in the department of emergency medicine  the University of Cincinnati, who presented the findings at the Society for Academic Emergency Medicine's annual meeting in Atlanta. "Our team hypothesized that when a patient was approached by a study assistant of the same race or sex, the patient would be more willing to participate than when race and sex were different."

To test this, the team studied nearly 160,000 patients screened for clinical research by 89 different study assistants at the UC Medical Center emergency department and Jewish Hospital emergency department from January 2007 to December 2011.

The patient population was 60 percent white and 44 percent male, while the study assistants were 75 percent white and 44 percent male. Most patients, 89 percent, were willing to be approached for research.

"We found that willingness to participate in research is influenced by the race and sex of the study assistant, but the impact is different for different groups," says Hart. "As researchers, we should be aware of the impact of race and sex on our relationships with study participants. The relationship is much more complicated than we thought it would be, and we hope to conduct further research to better understand the reasons behind our observations. It is important to ensure equal representation of all persons in clinical research and only by understanding the factors that influence willingness to participate can we begin to prevent bias."

The Impact Of Race And Sex Of Study Personnel On The Decision To Participate In Research. Co-authors are Andrew Ruffner, MPH, Carla McTaggert and Christopher Lindsell, PhD.