Politics, which can affect the dissemination and interpretation of data, can also affect the very existence of data, i.e., whether or not the data is collected in the first place.
The amount of money available today for studying the impact of firearms is a fraction of what it was in the mid-1990s, and the number of scientists toiling in the field has dwindled to just a handful as a result, researchers say.
The dearth of money can be traced in large measure to a clash between public health scientists and the N.R.A. in the mid-1990s. At the time, Dr. Rosenberg and others at the C.D.C. were becoming increasingly assertive about the importance of studying gun-related injuries and deaths as a public health phenomenon, financing studies that found, for example, having a gun in the house, rather than conferring protection, significantly increased the risk of homicide by a family member or intimate acquaintance.
Alarmed, the N.R.A. and its allies on Capitol Hill fought back. The injury center was guilty of “putting out papers that were really political opinion masquerading as medical science,” said Mr. Cox, who also worked on this issue for the N.R.A. more than a decade ago.