STUDIES:
70/
“While both high and low performing [Cincinnati officer] groups disproportionately stopped Black drivers, the low performing group had a significantly higher rate of racial disproportionality than the high performing group."

Race and Repeats: The Impact of Officer Performance on Racially Biased Policing
Journal of Criminal Justice
Vol. 35 Issue 4, pp. 405–417,
2007
Comment on this study on its Twitter thread.