D.C. violent crime by year, Jan. 1 to Feb. 16 only (Data and graphic: Urban Institute)

It’s good, accurate reporting that’s particularly valuable considering the D.C. police department’s crime stats Web site was down until recently for nearly two months. It also comes during a period where there was been a spate of armed robberies in upper Northwest neighborhoods where such activity has been historically rare. But like much reporting on short-term crime trends, it’s missing some context.

The Urban Institute, and its subsidiary D.C. Crime Policy Institute, provide some of that context in a blog post Thursday. Researchers Meagan Cahill and John Roman note, among other things, that the 40 percent figure is enhanced by the fact that violent crime was unusually low in January 2011 compared to any other month in the past 10 years.

Placed in the context of longer-term trends, the spike is notable and concerning but hardly evidence of a crime epidemic. The 882 violent crime incidents citywide between Jan. 1 and Feb. 16 remain less than the violent crime total for any year between 2000 and 2009. In the Second District, which includes upper Northwest to the west of Rock Creek Park, there were 37 robberies in that Jan. 1 to Feb. 16 period, still less than the 40 robberies in 2009 and much less than the 98 robberies in that period in 2001.

Cahill and Roman write: “We aren’t suggesting that violent crime is trivial or that it should be ignored. But an informed policy response should consider long-term trends and the volatile nature of crime over short-time periods. A spike in crime over a six-week period is not sufficient to suggest that the long-term downward trend in crime has reversed itself; it’s far too early to tell.”

Crime surges and retreats as the seasons change; the police react to new trends, and the criminals react in turn. But it’s helpful to keep in mind that in D.C. for the last decade, for every headline about a few weeks’ crime spike, there have been declines in violent crime that don’t get nearly as much notice.