In a continuing commitment to transparency and equitable policing, the Michigan State Police (MSP) today shared
an independent study of its 2021 traffic stop data conducted by researchers at the School of Criminal Justice at Michigan State University (MSU). This study, which follows a similar independent study conducted last year, explores racial and ethnic disparities both statewide and at the post level using the Veil-of-Darkness (VOD) research methodology.
Among researchers, the VOD is considered the leading approach to estimating disparities in traffic stops. The VOD works by assuming that police officers have more difficulty discerning the race/ethnicity of a driver based on visual appearance prior to a traffic stop when it is dark outside than when it is light outside. When performing a VOD analysis, only traffic stops that occurred during the intertwilight period, which is the earliest dusk to the latest sunset, are included in the analysis. This creates an experimental setting that leverages the seasonal variation in daylight to compare traffic stops made during daylight to traffic stops that occurred at the same time of day but during darkness (during a different time of year) for each racial/ethnic group.
Using this method, researchers found that traffic stops conducted in daylight were 11 percent more likely to involve an African American driver and 18 percent more likely to involve a Hispanic driver than those conducted in periods of darkness. When the analysis was restricted to only the 30 days before and 30 days after the switch, to and from, Daylight Savings Time (DST) to control for seasonal variation in driving patterns and traffic stop behavior across the year, the results revealed there were no racial or ethnic disparities in MSP traffic stops, which means that African American and Hispanic drivers were no more likely to be involved in traffic stops in daylight compared to darkness. While this difference in results seems to indicate that seasonal variation in traffic flow over the course of the year could explain some of the disparity observed in the analysis, the researchers note the results from this DST-centered re-analysis should be interpreted cautiously given it is based on only a third of the full traffic stop data within the original analysis, since it only reviews traffic stops made in a period totaling four months.
“Our goal continues to be fair and equitable policing for all,” stated Col. Joe Gasper, director of the MSP. “While this report provides us with additional understanding and awareness, continued research is needed to understand more fully what the data is telling us. As the study notes, there is a difference between disparity and discrimination and there may be legitimate reasons for any disparity in traffic stops, which is why continued research is so important.”
This most recent study, which analyzes MSP’s traffic stop data from 2021, followed a broader benchmarking study of the department’s 2020 traffic stops, released publicly in January 2022, which explored various research methodologies for analyzing the department’s traffic stop data.
Upon release of prior report, the
MSP committed to a series of steps that included continuing research to determine if current policies and systems were contributing to disparity for some drivers. Since the last report, the MSP has:
● Hired an independent consulting firm, CNA, to analyze traffic patrol operations to determine if existing policies, procedures and training are contributing to racial and ethnic disparities. Scheduled to conclude in December 2023, the 18-month study has included an in-depth review of MSP data, stakeholder interviews and focus groups, as well as ride-alongs with troopers that provide consultants with opportunities for direct observation of patrol operations in an effort understand the impacts of policies, procedures and training on equitable traffic safety.
● Engaged in open and honest conversation with leaders and community organizations from communities of color in cities including Detroit, Flint and Inkster to discuss concerns, build relationships and find solutions together.
● Launched a one-year pilot project at 17 posts that visually presents traffic stop data in a dashboard for troopers and their supervisors to view in real-time so they can gain awareness of their patrol activities. Researchers are currently studying the data collected during the pilot to determine if the use of the dashboard has an effect on reducing racial disparities in traffic stops.
● Established a Professional Development Bureau focused on training and development for enforcement members on familiar topics, as well as on new and emerging topics including mental health, wellness, de-escalation, cultural competency, decision-making, implicit bias and communication skills. In March 2022, the MSP trained all department members on the difference between race and ethnicity.
● Equipped enforcement members with body-worn cameras, two months ahead of scheduled deployment. Specifically, issued 1,635 body-worn cameras and conducted relevant training statewide for all MSP members who could have enforcement contact with Michigan residents and visitors. This deployment followed completion of camera and other technology upgrades in 1,320 patrol vehicles statewide.
In advancing the work of the last report, this report also includes a post-level analysis whereby each post was examined separately. While the post-level analyses do not account for seasonal variation in traffic flow and traffic stop behavior, the findings reveal that 21 out of 30 posts showed no evidence of racial or ethnic disparity in traffic stops. Even though the sample sizes for this post-by-post analysis is much smaller thereby providing researchers with less confidence in the results, these findings seem to indicate the disparity observed statewide is constrained to a handful of posts. Further analysis in future reports is needed to confirm these results and determine whether any legitimate factors explain the observed disparity at these posts.
“To live out our mission and advance our just cause, which is to contribute to a Michigan where everyone feels safe and secure, we are committed to continuing to research and analyze our traffic stop data in hopes of better understanding the complicated dynamics at play,” added Gasper. “Through the work we are doing, we’re advancing this field of study for all police agencies, and our approach will continue to be one of introspection, listening and learning.”
As a follow up to this year’s report, the MSP has committed to a long-term research partnership with the MSU School of Criminal Justice, pledging reviews of its traffic stop data for the next five years, which will further our understanding of the data and possibly begin to identify trends over time.
The next annual report will study the department’s 2022 traffic stop data, the first year for which GPS location data will be available for each traffic stop. This additional factor should provide for more nuanced examination of racial/ethnic disparity in future reports.
