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The problem is that the -16 swing falls within the 95% confidence interval. If the 95% confidence interval is -31.7 to -0.3, that means it is 95% likely that a variance of that magnitude will occur, and -16 falls right in the middle. I don't see what's so significant.
[/ QUOTE ] What the study authors did was try to establish the size of the effect of the smoking ban on heart attack rates. Based on the variation in observed heart attacks before and after the ban, they were able to say with 95% certainty that the true effect size was between -0.3 and -31.7.
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If the study did reflect something meaningful, they would have established the boundaries of standard deviation (for example, they could state that swings of +/- X, around the mean (in this case, 40 MCIs/month), fall within two standard deviations, or ~95%). Something occurring outside that boundary would be worthy of attention. If the 95% confidence interval was 50 to 30, then drop occurring outside that range (like 24 MCI/month) would have a frequency of <2.5%
[/ QUOTE ]What they did was an alternative to that. Both are statistically valid ways of analyzing what happened.
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Even if this were the case, it's still far from establishing correlation, let alone causation. If you're going to correlate smoking bans with decreases in MCI incidents, you need a sample size greater than one.
[/ QUOTE ]That's true, and even the scientists who wrote the study agree. As it turns out,
it was validated by a similar study in Pueblo. There are also extensive epidemiology studies showing greater risk to nonsmokers who breathe lots of second hand smoke.
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You need to compare the prevalence of changes in MCI incidents in towns that did employ smoking bans with similar changes in towns that did not employ smoking bans.
[/ QUOTE ] This is implied. There was no state-wide or nation-wide decrease in heart attacks during the same period.
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For example, the increase of late nineties ecstacy use among kids happened concurrently with the popularity of the teletubbies, and declined similarly. However, it's clearly erroneous to say that Tinky-Winky was causing kids to take molly and dance all night.
[/ QUOTE ] The correlation seen in this data is much more specific than a simple temporal co-occurence. Heart attacks decreased only in towns with smoking bans, and that decrease went away when the ban was lifted. I suppose it's theoretically possible that some unknown factor prevented all those heart attacks, but by far the most parsimonious explanation is that the second-hand smoke ban did it.
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Lastly, COME ON. Use a little common sense. If we are to believe that this evidence is indeed statistically valid, the conclusion of this study is that legally facilitated decreased exposure to second hand smoke in public places lowers the incidence of heart attacks by more than one third? AND that this is observable immediately?!?! Christ, it takes hardcore smokers years, even decades, before they start developing serious health problems, but somehow the absence of smoke in a bar results in an IMMEDIATE decrease of heart attacks?
[/ QUOTE ] I don't see why the idea that nicotine could be a proximate cause of heart attacks is so outlandish. Many fat people's hearts may be near the brink of heart attacks a lot of the time. If you expose them to a drug that increases heart rate, blood pressure and constricts the arteries, it just makes sense that that could push them over the edge.