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An investigator is studying an outbreak of ...

Only cookies are independently associated with E. coli cases🔍

An investigator is studying an outbreak of ...

Only cookies are independently associated with E. coli cases🔍

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Did no one notice that the Odds ratio on the top left is wrong? Am I missing something? If you calculate it, it's 6 just like the top right one....

b1ackcoffee
that fucking threw me off on exam. I was like is there an effect modification by "Not drinking milk". the fuck!
+

The fact that the odds ratio in the top left is incorrect makes this question very difficult. It makes it appear as if the cookies are causative but the milk had some protective factor. So obnoxious.

drpatinoire
God I thought totally the same way as you did. I stared at this question for at least 5min and asked myself what's wrong with my statistics.
+1

OR >1 indicates increased occurrence of event. The only OR greater than 1 was in the table that indicated that the subject ate cookies but didn't drink milk. Thus, that is the only one with a significant occurrence

For a more systematic approach. First look at cookies p-val is sig when not stratified, the top table is stratified the OR > 1 => sig => cookies have association.

Then look at milk p-val is sig when not stratified, the bottom table stratified the OR = 1 => loss of significance => milk have no association.

`Odds Ratio = 6`

, I believe), which when you looked at the labels, led to the right answer.

For people who generally had trouble reading the two charts:

First chart: We separated the entire population into two smaller populations to test for the cookies affect. In Population A (drank milk) there was an odds ratio of 6 (typo in the actual chart). In Population B (did not drink milk) there was an odds ratio of 6. Since the odds ratios are not 1, we can conclude that the cookies have an effect regardless of the population (ie drank milk people versus didn't drink milk people).

Second chart: New set of populations to test for the effect of milk. In Population C (ate cookies) there was an odds ratio of 1. In Population D (did not eat cookies) there was also an odds ratio of 1. This means that milk did not have an effect ever and didn't contribute to the disease.

"Only cookies are independently associated with *E. coli* cases" means that only the cookies cause the disease without the effects of something else.

The keyword is "INDEPENDENTLY"(associated). Which in human language means "NOT ASSOCIATED".

submitted by niboonsh(220), 2019-09-11T00:51:44Z

this question makes me want to eat an e coli cookie and hope i bleed out