Last week, the Brookings Institute came out with an update on the city’s progress on a landmark set of recommendations from back in 2006 on how to deal with the affordable housing shortage. The verdict was mixed: Some laws have been enacted and homes built, but the recession whacked most of the public subsidies for the creation and preservation of reasonably priced places to live. Considering that reality, the report’s authors made a new set of recommendations for how the District ought to proceed with the meager funds available.

What jumped out at me, though, was the uncertainty around how much affordable housing we even have. “It is not yet clear how the supply of affordable housing units in the District has changed since 2006,” the report reads. “Some housing advocates believe the city continues to lose affordable housing, while others believe the District is making progress.”

What? How can you believe different things about what should, theoretically, be a concrete number? In this case, the authors define “affordable” as a home that requires a person making less than 80 percent of the area median income to spend less than 30 percent of their income on rent or a mortgage, whether or not public funds are involved. The problem is, there’s no central clearinghouse for that kind of information—-which makes determining whether we’ve made any progress pretty much impossible.

Here’s what we do have: There’s the American Community Survey, which gives some data about how much housing exists and how much people are paying for it. There’s the Housing Authority’s dchousingsearch.org, which landlords can voluntarily add their properties for rent or for sale. And there’s a database maintained by the Deputy Mayor for Planning and Economic Development that’s supposed to catalogue all the housing developed or preserved using District funds. But its accuracy and comprehensiveness depends on how successful DMPED staff are at harassing the various agencies who deal with housing to enter properties into the system.

“That should be the best database for us,” says Brookings’ Benjamin Orr, who authored the report with District research doyenne Alice Rivlin. “The problem is that it’s not.”

To address that problem, a couple dozen housing-related advocacy groups have started the D.C. Preservation Catalog, which is supposed to be a parallel system that also documents things like inspection scores and whether a property is at risk of losing its Section 8 contract. But ultimately, wrote advocates in their transition report for the incoming Gray administration, the District should maintain the inventory and make it publicly accessible.

That seems like as concrete and fundamental a short term goal as you can get.