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#1




biostat problem regarding confidence intervals
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 95% confidence interval of 1.5 to 3.5. Patients receiving drug Y have a cardiac index of 1.7/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 mea 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% 
#2




10% (p=0.1)

#3




my answer :)
e. 10% = p value

#4




Is this question asking about likely hood of type 2 error???
If yes, then if p value is above 0.05 then type to error is not equal to p value. I think i am getting lost here. any insight??
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#5




There is an overlap of the confidence intervals between the two drugs. So statistically there is no significant difference in the efficiency of the two drugs.
Therefore I would go for answer g (95%) (its the maximum likelihood that the difference is due to chance, from the given options). I would go for 100% if it was listed as one of the options. I don't have the correct answer. Just my chainofthoughts. What do you think? 
#6




Quote:

#7




the problem is that I saw the answer sheet too like you but didn't agree with the answer. That is why I posted the question so that someone could explain the answer giving the appropriate reason. I still think it should be 95%. Anyone here with good knowledge in biostat who can explain?

#8




Quote:
"A test of the significance of difference shows a p value of 0.1." Then, they ask: "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?"  which is basically a textbook definition of type I error (alpha).Since alpha = p value, the answer is e. 10% 
The above post was thanked by:  
DrSK (11182012), koolkiller88 (11182012) 
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BiostatisticsEpidemiology, Step1Questions 
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