--- In [email protected], "authfriend" <[EMAIL PROTECTED]> wrote: > > --- In [email protected], akasha_108 <[EMAIL PROTECTED]> > wrote: > <snip> > > So when separate models are used to predict crime, distinct from the > > intervention model, its unconventional. Its not needed, unless there > > were severe data problems. Doing so weakens the predictive power of > > the model(s). > > > > There is nothing in the data issues, at first glance, that suggest > > why multiple, models were used. > > I have no idea what you're talking about when you > refer to "multiple models." I never said anything > about multiple models. see adjacent post in my response to LBS.
> You seem to say the prediction based on past trends > was unnecessary; but then to what do you compare the > actual crime rate during the period to determine > whether and how much it's been affected? If it was a short term model, then crime rates would be compared to the pre course "one month"* and the post course "one month". These would be control periods (not necessarily good ones, but thats another story.) *or whatever pre and post periods they used. I thought you yourself argued previously that long term data was not necessary (like abortion rates) because the effects were shown in a short-term time frame. Perhaps I misunderstood your prior point. If they had the pre and post periods, why did they need the "5 year" (or what ever longer term model) to estimate the crime rate without intervention? They had the "control" periods, pre and post. They didn't need to estimate a non-intervention period. See my adjacent post. I think the longer term model was a second stage of analysis used to control for weather. See my adjacent post. Its the only explanation that makes sense to me at this point. Actually reading the study would be halpful though, instead of specualation. > Here's a report on the study that may provide some > more detail, but there's not much about the > specific statistical methodology: > > http://www.mum.edu/m_effect/dc_md.html > ------------------------ 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/
