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  #1  
Old 05-25-2011
bebix's Avatar
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Stats Treatment vs control, the interpretation of the p-value

A study was carried out to investigate the effectiveness of a treatment. 1000 subjects participated in the study, with 500 being randomly assigned to the “treatment group” and the other 500 to the “control (or placebo) group”. A statistically significant difference was reported between the responses of the two groups (P < .005). Thus,

(a) there is a large difference between the effects of the treatment and the placebo.
(b) there is strong evidence that the treatment is very effective.
(c) there is strong evidence that there is some difference in effect between the treatment and the placebo.
(d) there is little evidence that the treatment has any effect.
(e) there is evidence of a strong treatment effect.
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Old 05-25-2011
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Ans (c) there is strong evidence that there is some difference in effect between the treatment and the placebo.

A, B & E are wrong because the p value doesn't tell you the effect of either the control or the drug, it just tells you whether there is a difference between the two, and how big that difference is.
D is wrong because the p value is pretty small, so strong evidence; hence C is correct

Last edited by heights; 05-25-2011 at 09:25 PM. Reason: Typo on the last line
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  #3  
Old 05-25-2011
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Quote:
Originally Posted by heights View Post
Ans (c) there is strong evidence that there is some difference in effect between the treatment and the placebo.

A, B & E are wrong because the p value doesn't tell you the effect of either the control or the drug, it just tells you whether there is a difference between the two, and how big that difference is.
C is wrong because the p value is pretty small, so strong evidence.
I think you mean C is right because the p value is pretty small, so strong evidence.
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Old 05-25-2011
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Originally Posted by patelMD View Post
I think you mean C is right because the p value is pretty small, so strong evidence.
Thanks for pointing that out, that was a typo on my part! I did mean C is right, but I also wanted to point out that's why D was wrong
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  #5  
Old 05-26-2011
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Correct Answer Correct Answer: C

Yeap i think is C as well.
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Old 05-26-2011
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Quote:
Originally Posted by heights View Post
Ans (c) there is strong evidence that there is some difference in effect between the treatment and the placebo.

A, B & E are wrong because the p value doesn't tell you the effect of either the control or the drug, it just tells you whether there is a difference between the two, and how big that difference is.
D is wrong because the p value is pretty small, so strong evidence; hence C is correct
You are all correct!, the right answer is C)...perfect explanation above
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