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#1
08-05-2012
 USMLE Forums Master Steps History: 1+CK+CS Posts: 1,867 Threads: 149 Thanked 2,107 Times in 1,049 Posts Reputation: 2127
This disparate finding

A researcher publishes new results on the efficacy of a procedure using transplanted embryonic cells to correct
a diabetic condition induced in experimental animals by chemical ablation of pancreatic beta cells. At another
institution, a different researcher attempts to reproduce the findings, but cannot. This disparate finding calls into
question the first study's

A. accuracy

B. power

C. reliability

D. sensitivity

E. validity

#2
08-05-2012
 USMLE Forums Addict Steps History: 1+CK+CS+3 Posts: 151 Threads: 48 Thanked 112 Times in 60 Posts Reputation: 122

Reliability..C
#3
08-05-2012
 USMLE Forums Master Steps History: 1+CK+CS Posts: 1,867 Threads: 149 Thanked 2,107 Times in 1,049 Posts Reputation: 2127

Explanation:

The correct answer is C. The reliability of a measurement refers to the ability of other researchers to reproduce
the results.
This can be summarized by noting that reliability = reproducibility.

Random error-reduces precision in a test.
Precision is:
l. The consistency and reproducibility of a test (reliability)
2.The absence of random variation in a test

The accuracy (choice A) of a measurement refers to the "trueness" of the measurement, i.e., how close the
measured value is to the true value
. It is a measure of bias. Just because another researcher could not
reproduce the findings does not necessarily imply that they were inaccurate.
Accuracy is the trueness of test measurements (validity). Systematic error-reduces accuracy in a test.

The power (choice B) of a study is best conceptualized as the probability of rejecting a null hypothesis that is in
fact false
. This is equal to 1 minus the probability of a type II error (1-&beta, since &beta; is the probability of
failing to reject a false null hypothesis. If you increase sample size, you increase power. There is power
in numbers.

The sensitivity (choice D) of a test is a measure of its ability to detect the presence of a disease in those who
truly have the disease.

The validity (choice E) of a measurement is an index of how well the test measures what it purports to measure.
The disparate results obtained by another researcher do not necessarily mean that the results are not valid.

Last edited by Novobiocin; 08-05-2012 at 03:29 PM.

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