Re: Really?
Link for the study referenced:
https://www.repository.cam.ac.uk/bitstream/handle/1810/260710/Ariel_et_al-Journal_of_Criminal_Justice_and_Behavior-AM.pdf?sequence=1
The differences between the two studies are stark. In the study with this article, DC police were selected based on some arbitrary criteria (including whether they had scheduled leave and either an administrator or beat-cop). They only compared the non-camera control group to the those wearing cameras. And use of the camera was essentially voluntary ("[they] shall start... as soon as a call is initiated... or at the beginning of any self-initiated police action").
In the Cambridge study you reference, EVERY officer in the departments either wore cameras or not (based on duty shift). In addition to comparing to the control groups, they also looked at overall department-wide effect (across seven different departments). And use of the cameras was compulsory and continuous. Also, of course, Cambridge University is widely recognized as a top-notch research facility, at least when compared to the mayor's office of Washington DC (specifically, "Office of the City Administrator's Office of Performance Management").