saxitoxin wrote:As I stated, it doesn't affect the data result, it affects the conclusion. The conclusion being "the probability of success may be low" with the implication of the discussion being this conclusion is valid outside the city limits of Philadelphia. Unless Philadelphia represents the demographic mean of all U.S. urban, suburban and rural areas - which it does not in at least one category (absolute crime rate), and most likely in many others as well - the study is of marginal value. This point is aside, however, from the more important fact that ...
I agree with this general conclusion about the limited potential applications of the study (and so do the authors). It's still a strong argument to inform government policy in urban areas.
This confirms the suspicion I originally stated -
However, compared with control participants, shooting case participants were signiﬁcantly more often Hispanic, more frequently working in high-risk occupations, less educated, and had a greater frequency of prior arrest. At the time of shooting, case participants were also signiﬁcantly more often involved with alcohol and drugs, outdoors, and closer to areas where more Blacks, Hispanics, and unemployed individuals resided.
As I stated, the overrepresentation of these groups was accounted for and weighted appropriately when generating the results. They were fairly vague on the statistical method used to weight these factors, however.
U Penn study wrote:Finally, as this was a case–control study, we had the advantage of being able to statistically adjust for numerous confounders of the relationship between gun possession and gun assault. These confounders included important individual-level factors that did not change with time such as having a high-risk occupation, limited education, or an arrest record. Other confounders that we included were situational factors that could have influenced the relationship under study: substance abuse, being outside, having others present, and being in neighborhood surroundings that were impoverished or busy with illicit drug trafficking. Although these situational confounders were potentially short-lived (e.g., a participant may have metabolized the drugs or alcohol they consumed, moved to another location, or left
the company of others) this was less important given the incidence–density sampling and the fact that case and control participants were essentially matched on time.