Subway crime remains at record-low levels.

So it was confusing that the Metropolitan Transportation Authority board voted this week to hire 500 additional police officers to patrol the subway and other parts of the transit system, diverting an estimated $250 million over four years in precious funds that should go toward improving service.

While more than 2,500 New York City police officers now patrol the subways, Gov. Andrew Cuomo and M.T.A. officials have said the transit authority needs to add hundreds of their own officers because of an increase in crime and quality of life problems. The facts don’t bear that out.

Serious crime is down more than 4 percent from last year, according to the New York City police. Felony assault complaints are down, as are grand larcenies. Though robbery complaints are up roughly 10 percent, that represents an additional 46 robberies. There have been three murders and three rapes — six horrific crimes too many, but also evidence that a system used by millions every day is impressively safe.

Though Mr. Cuomo and M.T.A. officials have argued that misdemeanors are on the rise, the preliminary findings of an analysis by the Brennan Center for Justice at New York University’s law school found that their number has been roughly the same over the past seven years, Politico reported.