--- In [email protected], "authfriend" <[EMAIL PROTECTED]> wrote: > > --- In [email protected], "markmeredith2002" > <[EMAIL PROTECTED]> wrote: > > > > > > > If the DC crime rate was > > > > > relatively flat during the 90s, maybe that's an ok > methodology. But > > > > > metro cities throughout the nation experienced a dramatic > drop in > > > > > crime rate starting around 1992-1993 and continuing for > several yrs > > > > > and therefore the study can't prove its point w/o controlling > for > > > > > this major factor. > > > > > > > > They did, by "predicting" what the crime rate *would* have > > > > been for that period that year on the basis of the previous > > > > five-year trend. It's true that there might have been > > > > *somewhat* less of a reduction if the crime rate had started > > > > going down in early 1993, but you would have no reason to > > > > see the sharp, sudden drop they measured during the project > > > > on the basis of the decline you're talking about (much less > > > > the return to "normal" a few weeks after the study). > > > > The 5 yr trend is meaningless - the trend for violent crime was > > significantly up during the 80s and then it unexpectedly and > > dramatically turned down in the 90s, then flattened out near the end > > of that decade. All sorts of studies came out in the 90s supposedly > > proving that this or that particular program was reducing crime in > > this or that city, but in retrospect we now know that crime was > > going down in all large cities, even ones not doing this or that. > > Wow. You're still not getting it, and I'm not sure > how to clear it up for you. Maybe you could just try > reading what I wrote above a little more carefully. > Everything you just said is utterly irrelevant in the > case of this study.
I think Mark's point is, similar to mine a month ago on this topic, if a model to estimate (weather and other factor) normalized crime rates for the intervention period were developed, it would have to be a multi-year model at least five years or so -- longer would be much better. (I used to help develop such weather normalized models, and used them and 20-30 + years is the norm) And if such long term normaized models were used, even if only 5 years, they would need to include the abortion effect variables (sub-cohorts for 16-22 yr olds with mothers who gave birth as teens, were at low income and education levels, single, etc.) and now known crime-factors, in order to be useful and accurate. > If the crime rate were trending down over those five > years, or just the last two of those years, it would > be reflected in the "prediction" of what the crime > rate *would have been* if the project hadn't been > conducted during those eight weeks. I know you (probably) don't see it because you have never done this type of analysis (I assume), but what you just said suggests two models: a long term model to estimate (not predict that references the future) a weather normalized crime rate and a short term impact model. Normally this would NOT be a separate step and NOT two models. A single well constructed model would control for weather, sociological and crime-factor variabes, and the intervention variable, ALL AT THE SAME TIME. Apparently, for reasons not clear, they did not do this. If they predicted a normaized crime rate, then thiis is one model. To test the impact variable, ME, there has to be a second model. > > I'm saying the study design needs to be revisited due to what we now know about the unique crime trends in the 90s. > > Nope, not for an eight-week World Peace Assembly. How are you going to control for weather effects then? You need a longer term model to do that. As well as for other crime factors. > Now, *that's* entirely reasonable. (The data itself is > public; Is it. How can I acess it? > what you want to see is how they set up the time- > series analysis and what the results were.) > > > OF course, akasha is right that even if the statistics hold, you > > still need more studies looking at it from different angles. > > Of course. Akasha is always right. :) > > > So what's going to be the practical result of all these half or 3/4 > > baked M-effect studies? > > Basically nothing (except that some of them are a > little better-cooked than you think). But they're > pretty interesting to discuss. Yes, as an exploratory study, they might actually show enough promise to warrant more research. The larger research community doesn't think so, but who knows. ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/JjtolB/TM --------------------------------------------------------------------~-> To subscribe, send a message to: [EMAIL PROTECTED] Or go to: http://groups.yahoo.com/group/FairfieldLife/ and click 'Join This Group!' Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/FairfieldLife/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
