Race’s status as an umbrella term for an amorphous category of qualities — from skin color to lifestyle choices — justify a significant degree of skepticism about claims of racial profiling. In the context of a recent University of Rhode Island investigation of state police traffic stops and searches (concerning which, I haven’t been able to find more detail than that provided in today’s Projo story), for example, there are various factors that could correlate with race and that would be of varying degrees of culpability when it comes to motivation for searches.
Suppose 90% of all people who were stopped and whose cars were searched were — as we used to call them — hoodies. A presumption of increased likelihood of finding something suspicious or illegal in the car is thus premised on visual clues about the character of the driver and the cultural significance of his or her comportment. Perhaps that oughtn’t be grounds for searches, but it’s certainly less sinister than the specter of racism, and general experience suggests that the criterion would affect races disproportionately. Driving habits and attitudes are other examples of factors that might inherently select for race without indicating racism (unless, as advocates and activists like to do, one treats them as definitional of a people).
Of course, for the analysis to be fair, we’d need more information than is available. Perhaps the presumption that hoodiness correlates with criminality is mistaken, thus making it an unfair reason to treat motorists differently. To answer the question, however, one would have to pull over and search random cars; if more hoodies have contraband, then the profile is reasonable. (In point of fact, we are operating under just such experience, albeit without the mooring of scientifically collected data.)
What numbers the Projo article does supply confuse more than they enlighten:

The authors conclude that if two drivers, one white and the other black, were driving vehicles of the same age, with no passengers, on similar roads in the same area at the same time of day, the black driver would be 1 1/2 times as likely to be pulled over as the white driver by troopers from the same state police barracks. Hispanic drivers would be slightly more likely to be stopped. …
The study found “substantial evidence of racial and ethnic disparity” in searches where troopers had discretion in whether to search, and said there was little change from the previous studies. Blacks were twice as likely to be searched as whites, and Hispanics 1 1/2 times as likely. After adjusting for a number of factors that could explain some of the difference, the authors said, Hispanic drivers were no more likely to be searched, but blacks were still 1 1/2 times as likely to be searched as whites.
However, despite the more-frequent searches, no more contraband (mostly drugs) was found among nonwhites than among whites.
The fact that troopers searched black drivers more often than whites but found no more contraband, the study says, suggests that there was less legal basis for searching the blacks. In fact, the state police found drugs and other contraband slightly more often in the vehicles driven by whites as in those driven by minorities. (Contraband was found in vehicles driven by: whites, 42.9 percent; blacks, 42.2 percent, and Hispanics, 40.5 percent.)

Obviously, those percentages cannot be of the total number of drivers, because that information is not possible to collect, so they must represent the portion of either stops or searches. If they are percentages of those stopped, then they are noteworthy, because every car stopped but not searched would go into the “clean” category, and fewer minority-driven vehicles were not searched.
More likely, however, they are percentages of cars searched, meaning that more contraband was found in the minority-driven cars, in absolute terms. In that case, impropriety only exists if additional searches of white-driven cars would maintain the police’s find rate for that group.
Reporter Bruce Landis writes that the study’s “results are consistent with what one would expect from biased law-enforcement tactics,” but given the very narrow range of discrepancy in these percentages, they are also consistent with what one would expect if state police officers’ instincts are of roughly equal accuracy across races, but are more often triggered by drivers in minority groups.
The prescription for remedying that problem lie beyond the boundaries of law enforcement.