MAYOR GAVIN NEWSOM proudly announced Feb. 14 that the city had seen a precipitous decline in the number of homeless people, from 8,640 in 2002 to 5,642 this year. Even better, according to Newsom, were the statistics showing that only 2,655 people were actually living on the streets (the rest were in some sort of program or shelter). Those numbers came from a census the city must now conduct every year to qualify for federal assistance. Some 250 city workers fanned out across San Francisco one night to take the count, which the Mayor's Office defends as fair and as accurate as possible, given the difficulty of tracking a transient population.

The Coalition on Homelessness has a different take on the numbers. As Chance Martin notes in an opinion piece on this page, the census ignored the large number of people who sleep in city parks (off-limits to the counting crew) and the final tally was almost certainly low.

Still, there's a pretty good chance that the actual population of homeless people in San Francisco has, indeed, declined since Newsom's punitive Care Not Cash program went into effect last year. Although the mayor and many of his backers piously assert that the plan is simply a compassionate way to help the unfortunate, CNC was clearly designed to drive as many homeless people as possible out of the city – and it's not surprising that it's succeeded.

Since the program began, some 1,818 people have lost their General Assistance benefits. Nobody knows exactly what happened to all of them; the city hasn't made the effort to track them down. Some are probably still on the streets, panhandling more aggressively and resorting to crime to come up with enough money for survival. Some may have moved to Alameda or Contra Costa counties, both of which say they are expecting to see an increase in the number of homeless on their streets.

Newsom says the big drop is a sign that Care Not Cash is working – that people are getting off the streets and into supportive housing. And, indeed, city officials have placed 690 people into something resembling permanent housing, and of that Newsom can be justifiably proud. But before the mayor crows too loudly about his policy success, he needs to make sure that all of the facts are in.

This is a program with national implications – if a city as liberal as San Francisco can take a tough-love approach to homelessness and prove that it works, politicians all over the country will be emboldened to reduce urban welfare payments, force people into possibly dubious shelter programs, and crack down on anyone who sleeps on the streets.

So it's absolutely critical that the city do a full investigation of where every one of those 2,998 people who were counted in 2002 and are missing in 2004 wound up going. How many are now in Oakland, or Berkeley, or Hayward, or Daly City? How many left California altogether? How many have gone deep underground, hiding in places were the census-takers can't find them, living the shadowy lives common in third world cities? Has Care Not Cash really helped – or has it just created problems for other cities and driven the most marginal residents of San Francisco further away from any sort of social service?

The supervisors should demand that Newsom's next budget include a comprehensive study that tracks the beneficiaries and victims of CNC. If he can't do that, then the program that defined his mayoral campaign will remain unproven at best, a cruel failure at worst.

P.S. The number of homeless in San Francisco is about to go up. As Rachel Brahinsky reports, a Mission District landlord is evicting 17 people from a building that has been used as a rooming house for two decades. The landlord argues – correctly – that the place isn't up to code and that too many people are packed illegally into too little space. But that doesn't change the fact that a group of low-wage workers who accepted cramped, illegal living conditions as a better choice than homelessness are about to be forced onto the streets. If landlords who buy places that have illegal units in them decide to evict those residents (who have been paying rent in good faith, sometimes for many years), the city should at the very least require those landlords to pay substantial relocation fees and help the tenants find new housing. Or else Newsom's numbers will keep going up.