Biostatistics #9 - Confounding, effect modification and adjusted analysis - USMLE Forums
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  #1  
Old 06-04-2011
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Stats Biostatistics #9 - Confounding, effect modification and adjusted analysis

The relative risk of ischemic stroke for non-whites compared with whites is about 2 for those aged 35 to 64 years and about 1 for those 65 years of age and above. This is best described as:

a. confounding of the effect of race by age
b. modification of the effect of race by age
c. elimination of the effect of race by age-adjustment
d. elimination of the effect of age by race-adjustment
e. all of the above
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Old 06-04-2011
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Quote:
Originally Posted by bebix View Post
The relative risk of ischemic stroke for non-whites compared with whites is about 2 for those aged 35 to 64 years and about 1 for those 65 years of age and above. This is best described as:

a. confounding of the effect of race by age
b. modification of the effect of race by age
c. elimination of the effect of race by age-adjustment
d. elimination of the effect of age by race-adjustment
e. all of the above
C??? Elimination of effect of race by age.
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C??? Elimination of effect of race by age.
I'm with you
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C perhaps?
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My answer is B)
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Ccccccccc
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Hi.
I think the answer is C)
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why not a??
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@bebix, I really need to know the answer here :sorry::sorry:
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Correct Answer correct answer

Correct answer:

a. confounding of the effect of race by age
b. modification of the effect of race by age
c. elimination of the effect of race by age-adjustment
d. elimination of the effect of age by race-adjustment
e. all of the above[/QUOTE]

Remember:
Effect Modification (aka statistical interaction) occurs when the effect measure depends on the level of another factor.
or (in other words)
Effect modification occurs when our chosen summary of association differs in different strata.

Here we have 2 strata (levels):
1.- "young 35-64y/o" = RR of ischemic stroke for non-whites compared with whites is 2
2.- "old >64" y/o" = RR of ischemic stroke for non-whites compared with whites is 1
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Quote:
Originally Posted by bebix View Post
Correct answer:

a. confounding of the effect of race by age
b. modification of the effect of race by age
c. elimination of the effect of race by age-adjustment
d. elimination of the effect of age by race-adjustment
e. all of the above

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Quote:
Originally Posted by bebix View Post
The relative risk of ischemic stroke for non-whites compared with whites is about 2 for those aged 35 to 64 years and about 1 for those 65 years of age and above. This is best described as:

a. confounding of the effect of race by age
b. modification of the effect of race by age
c. elimination of the effect of race by age-adjustment
d. elimination of the effect of age by race-adjustment
e. all of the above

very smart question
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Originally Posted by drciri View Post
@bebix..
whenver u come up with this kind of Q`s..i really get depressed abt my prep..
kidding,but u come with always interesting Q`s.keep going.thank u
Thanks
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The relative risk of ischemic stroke for non-whites compared with whites is about 2 for those aged 35 to 64 years and about 1 for those 65 years of age and above. This is best described as:

a. confounding of the effect of race by age
b. modification of the effect of race by age
c. elimination of the effect of race by age-adjustment
d. elimination of the effect of age by race-adjustment
e. all of the above

is it B?
Becoz as the relative risk in persons 35-64 is 2 ,it means that there is increase chances of developing disease in the non-whites compared to whites...also the relative risk in persons 35-64 years is 1 it means that there is no difference between the non-whites and whites..
So,i am thinking that the race factor is affecting the outcome of the results..
i am not sure about it..Is my reasoning right??
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oops..too late for the answer..

just saw it..:sorry:
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Quote:
Originally Posted by struggle View Post
oops..too late for the answer..

just saw it..:sorry:
But your answer was correct!


"So,i am thinking that the race factor is affecting the outcome of the results"...well, actually the age variable is affecting the outcome
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Bebix, i implore you to post MORE questions like yours in stat PLEASE :sorry:
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Originally Posted by docoftheworld View Post
Bebix, i implore you to post MORE questions like yours in stat PLEASE :sorry:
haha...OK

try Qs 11 & 12 for now
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  #19  
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aye aye sir
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