mjl1717
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What exactly is an odds ratio??
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| almina
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odds ratio - calculated in retrospective case-control studies.
lets say odds ratio is equal to 2 - means that a person with disease is 2 times more likely to have had a certain risk than a person without the disease.
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| mjl1717
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Just to add to that briefly)
Its similar to relative risk
Literally:
It compares people with the disease(cases) with otherwise similar people without the disease(controls), attempting to look back into the past to see if a possible risk factor is found more frequently among cases then controls!
It is the ratio of the odds that a case was exposed to the odds that a control was exposed.
Mathematically
{Draw the disease vs risk factor box}
*
# of cases exposed to risk factor{A} (times) # of controls not exposed{D}
_____________________________________________________________# of controls exposed to risk factor{B}(times)# of cases not exposed{C}
An odds ratio of 1 indicates that a person with the disease is no more likely to have been exposed to the risk factor than is a person without the disease,suggesting that the risk factor is not related to the disease.
An odds ratio of less than 1 indicates that a person with the disease is less likely to have been exposed to the risk factor than is a person without the disease, implying that the risk factor may actualy be a "protective" factor
against the disease.
Remember we are looking back in the past.
:shock:
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| Alina T
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thank you for the quick refresh mjl! 
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