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#1




Biostat  p value
A report of a clinical trial of new drug for HSV2 vs a placebo noted that new drug gave a higher proportion of success then placebo. Report ende with a statement:chisq = 4.72, p=<0.05. So, we may conclude that
A) fewer than 1 in 20 will fail to benefit from the drug B) the chance hay an individual patient will fail to benefit is less than 0.05 C) if the drug were effective, the probability of the reported finding is less than 0.05 D) if the drug wer ineffective, the probability of the reported finding is less than 0.05 E) null hypothesis is false Do explain.. How to improve Biostat, it one of my weak subject?
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#2




where did u get this question?
E] is an answer for sure, 100%,, since the p is less than .05, u have to reject the null, which means it's false but also D] could be correct,,, if the findings were due to an [alpha error],,, the probability of that is also less than .05 so??
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#3




on second thought, he said nothing about results if they were more or less than [p], se we cant decide to accept or reject the null, i guess its only [D] left
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#4




my answer
Quote:
Ok, here's my approach. I would ignore chisq and pay attention to pvalue only. It's < 0.05, which = type I error = if we reject the null hypothesis there is <0.05 chance we will be wrong = if we say that there is a difference btw effectiveness of placebo and the drug, there is <0.05 chance that the drug is actually no better than placebo. The wording of the answers is bizarre to me.. 
#5




my answer is D.....p value less than 0.05 means we reject null hypothesis and the probability of error is <0.05.
and reg option E...we cannot say that null hypothesis is true of false. you just reject or fail to reject it. Rejection does not necessarily mean its false....!!!!
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#6




yeah it's D
it can't be E because you can't be 100% sure that the null hypothesis is false, even if the pvalue<0.05, there's still a 0.05 chance that it's true ! 
#7




Correct answer is D
Nice Explaination casandra. It's from Kaplan notes review I couldn't understand the Explaination Quote:
Look at pvalue <0.05  reject null hypothesis chance of type I error probability of error if the drug is not better than placebo is same as pvalue i.e, in this case 0.05 >0.05 do not reject the null hypothesis Remember you never accept null hypothesis nor term it as true or false in that case you are likely to encounter type II error which is not related pvalue. Type II error=1statistical power(do not confuse power with pvalue, power is given as % unlike pvalue)
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The above post was thanked by:  
Casandra (06202012) 
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