More telling than the stop statistics are the frisk statistics and the outcomes of the frisks. Police officers aren't supposed to frisk a subject who has been stopped unless the officer reasonably suspects the subject is armed. What is it about being black or Hispanic that makes officers more suspicious that subject has a weapon?

The study demonstrates that the higher frisk rate for black and Hispanic subjects of traffic stops is not justified by the results of the searches.

Frisked African Americans are 42.3% less likely to be found with a weapon than frisked whites and that frisked Hispanics are 31.8% less likely to have a weapon than frisked non-Hispanic whites.

The sensible conclusion is that LAPD officers as a whole tend to be more suspicious of black and Hispanic drivers, and that the greater suspicion is unfounded. As Ayres explains:

It is implausible that higher frisk and search rates are justified by higher minority criminality, when these frisks and searches are substantially less likely to uncover weapons, drugs, or other types of contraband. Independent of racial disparity, it is a sign of ineffective policing to have officers engage in such a large number of fruitless searches.

LAPD rejects the study, noting that it is based on four-year-old data. That argument is disingenuous, given LAPD's refusal to release more recent data about the department's stops and frisks.

This is the bottom line:

The report shows that people of color in Los Angeles experience harsher treatment by police that doesn’t appear to be justified by any legitimate law-enforcement concerns. The L.A.P.D. can’t just deny that racism is involved and let the matter rest; it should take steps to address that inequality.

Don't hold your breath waiting for that to happen.