docswapna
Forum Senior
Topics: 61
Posts: 229
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Two experimental drugs, drug X and drug Y, are being evaluated for
treatment of congestive heart failure. Patients receiving drug X have a cardiac index of 2.5 L/m2 with a 95% confidence interval of 1.5 to 3.5. Patients receiving drug Y have a cardiac index of 1.7 L/m2 with a 95% confidence interval of 0.7 to 2.7. A test of the significance of difference shows a p-value of 0.1. Which of the following is the likelihood that the difference in mean cardiac index of patients receiving drug X and drug Y is due to chance?
A. 0%
B. 2.5%
C. 5%
D. 7.5%
E. 10%
F. 66.7%
G. 95%
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| Allymd
Forum Senior
Topics: 15
Posts: 118
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Wow it is tough! hehe.. do you have the answer?? I wouldnt know exactly, but would be one of the highest one... F or G.
First, p value is not significant to reject the null hypothesis, but we are not given the statistical power to determine the risk for a B error. And also, the confidence interval for drug Y have 1.0 as a value, so it means it has no significance. I would go with G... what do you think guys?
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| X-Ray
Forum Senior
Topics: 25
Posts: 139
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A
and of course I see number and I WHAT ?
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| Ivil
Forum Senior
Topics: 8
Posts: 169
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p value = the probability that the given null hypothesis is true.. the question asks the likelihood that the difference in mean cardiac index of patients receiving drug X and drug Y is due to chance (null hypothesis)..
so the ans is E. 10%
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| HILFIGER
Forum Senior
Topics: 21
Posts: 192
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http://www.prep4usmle.com/forum/thread/41711
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| Ivil
Forum Senior
Topics: 8
Posts: 169
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or is it 0% because there is no possibility of type 1 error as the null hypothesis is not rejected..
me confused now...
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| IceAge
Forum Senior
Topics: 21
Posts: 159
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agree with Ivil ... 10% chance
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| lilla
Forum Senior
Topics: 26
Posts: 153
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the chance of a type 2 error can not be directly estimated from the p-value. but can ba calculated by substracting power from 1-power. here the power is 95%. so I think the correct answer is 5%.
please give us the correct answer. it would be nice! thanks a lot!
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| klimt
Forum Guru
Topics: 27
Posts: 605
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I go with E=10%
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| MRMAVERICK
Forum Guru
Topics: 41
Posts: 724
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any one wid the answer
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| kotikoti
Forum Newbie
Topics: 3
Posts: 23
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E
you don't have to do any calculations for this. Pvalue is .1, not significant. probability of being due to chance is 10%
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| Palaniappan
Forum Senior
Topics: 30
Posts: 148
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Yes..Answer E...Null hypothesis is the occurrence of the event due to chance...Pvalue is the probability of null hypothesis being true .
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