 Other researchers have looked for this "Ferguson effect" in the rise in crime rates and failed to find evidence for it on a national level.A report over the increased homicide rate in St. Louis concluded there was an "absence of credible and comprehensive evidence" for the Ferguson effect being responsible for that city's homicide increase.John McWhorter wrote that the Black Lives Matter movement had "done the nation a service" by bringing national attention to police killings of unarmed African Americans, and he encouraged it to expand its focus to include "black-on-black crime".