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Exposure Vs. Disease: Odds ration question
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GERD is the disease.
You are comparing exposure vs. non-exposure. If you were given no other information, one would assume a case with obesity constitutes "exposure."
To make your life easier you can ignore the middle two columns.
Have disease Don't have disease
(BMI >35) 400 100
(BMI <25) 100 400
Odds ratio is the odds you get disease with the exposure in question here (BMI > 25) divided by the ratio of the control. a/b / c/d or ad/bc
Odds ratio should be 16.
At least that's how I would have done it.
You are comparing exposure vs. non-exposure. If you were given no other information, one would assume a case with obesity constitutes "exposure."
To make your life easier you can ignore the middle two columns.
Have disease Don't have disease
(BMI >35) 400 100
(BMI <25) 100 400
Odds ratio is the odds you get disease with the exposure in question here (BMI > 25) divided by the ratio of the control. a/b / c/d or ad/bc
Odds ratio should be 16.
At least that's how I would have done it.
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You could also wait until you cover it in class as you will likely have more explanations and examples. Aren't you an M1?
W
webgenius
You're right the question is confusing.
What is the source of it anyway?
the odds ratio = odds that the group with the disease was exposed to a risk factor / odds that the group WITHOUT the disease was exposed to the SAME risk factor!
You can twist the question and consider that the risk factor is BMI > 35 and no risk factor is BMI < 25
people who developed GERD when exposed to the risk factor (BMI > 35) = 400 (a)
people who didn't develop GERD when exposed to the risk factor = 100 (b)
people who developed GERD when NO risk factor (BMI <25) = 100 (c)
people who didn't develop GERD when NO risk factor = 400 (d)
Disease
+ -
Risk factor + 400 100
- 100 400
so the odds ratio = (a/c) / (b/d) = 4 x 4 = 16
everything I wrote might be wrong loool cuz I just made it up I'm not sure about it 😛
What is the source of it anyway?
the odds ratio = odds that the group with the disease was exposed to a risk factor / odds that the group WITHOUT the disease was exposed to the SAME risk factor!
You can twist the question and consider that the risk factor is BMI > 35 and no risk factor is BMI < 25
people who developed GERD when exposed to the risk factor (BMI > 35) = 400 (a)
people who didn't develop GERD when exposed to the risk factor = 100 (b)
people who developed GERD when NO risk factor (BMI <25) = 100 (c)
people who didn't develop GERD when NO risk factor = 400 (d)
Disease
+ -
Risk factor + 400 100
- 100 400
so the odds ratio = (a/c) / (b/d) = 4 x 4 = 16
everything I wrote might be wrong loool cuz I just made it up I'm not sure about it 😛