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<div>Originally Posted by <strong>heathergirl67</strong> <a href="/community/forum/post/15444582"><img alt="View Post" class="inlineimg" src="/community/img/forum/go_quote.gif" style="border:0px solid;"></a></div>
<div style="font-style:italic;">I googled Bonferroni adjustment. I still don't get it. What's sad is that it's probably something kids learn in high school and I'm sitting here like <img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/headscratch.gif" style="border:0px solid;" title="headscratch"></div>
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No, sorry. It's a statistical term that one would not learn until, probably, a college-level stats class.<br><br>
Basically, it means that when you run a lot of tests (like the 42+ they ran), you have to adjust the p-value to account for that. The p-value is typically set at .05, which means that for something (a difference between the 2 groups) to be accepted as statistically significant, the probability of that difference being due to chance is less than 5 in 100. Well, if you run 42+ tests, SOMEthing will come up significant, just because you've run that many tests. (and, with a p-value of .05, 5 tests out of 100 would come up significant, just due to chance). So, a Bonferroni adjustment, you divide the p-value by the number of tests you run.<br><br>
.05/42 = .0011<br><br>
None of their results would be significant if they had done a Bonferroni adjustment.<br><br>
A good peer review should have stopped that paper right there. We make our undergraduate honors candidates use Bonferroni adjustments when they run more than 4 or 5 tests!<br><br>
Although one might argue that it would still be publishable withOUT finding any differences between the lesser vaxed group and the most vaxed group, as this is the type of finding that the CDC would use as "evidence" that vaccines are "safe."<br><br>
As the study stands now, the 2 groups - lesser-vaxed and more vaxed - were different on SES and mother's education (favoring the more vaxed group), and the differences on the neuropsy tests that favored the vaxed group all but disappeared when they statistically accounted for SES and income. The ONE difference that is left is the one they should not have accepted had they done a Bonferroni adjustment.<br><br>
HOWEVER, the fact that the lesser-vaxed group had lower SES and lower mother's education means that it is NOT a good comparison group to the lesser-vaxed children of today. (not sure whether someone may have already said this up-thread)
