Question

what is the correct answer..

1- In raising the cutoff point for a screening test, which of the following is the likely result?

A	An increase in sensitivity
B	An increase in specificity
C	An increase in false positives
D	An increase in prevalence
E	An increase in lead time bias

2- If the screening test does not delay the time of death from a condition but makes survival appear longer because of earlier detection of disease, there is evidence of

A	confounding
B	length-biased sampling.
C	lead time bias.
D	selection bias.
E	information bias.

3- A test with an LR+ of 15 can be said to provide evidence to

A	rule in the condition of interest.
B	rule out the condition of interest
C	make an earlier diagnosis.
D	prolong survival after diagnosis
E	detect slowly progressing forms of the condition of interest.

4- A specific diagnostic test is one that

A	has a high proportion of false-negative results.
B	has a low proportion of false-negative results.
C	has a high proportion of false-positive results.
D	has a low proportion of false-positive results.
E	none of the above.

5- A diagnostic test with no discriminatory ability would have an area under the ROC curve of

A	0.
B	0.25.
C	0.5.
D	1.
E	2

6- A diagnostic test with an LR- of 0.05 can be said to provide evidence to

A	rule in the condition of interest.
B	rule out the condition of interest.
C	make an earlier diagnosis.
D	prolong survival after diagnosis.
E	detect slowly progressing forms of the condition of interest

7- If a screening test does not delay the time of death from a condition but makes survival appear longer because it is preferentially detecting slowly progressing disease, there is evidence of

A	confounding.
B	length-biased sampling.
C	lead time bias.
D	selection bias.
E	information bias.

8- Two screening tests are being compared for a particular disease. Test A has an area under the ROC curve of 0.95. Test B has an area under the ROC curve of 0.83. Which of the following statements is correct?

A	Neither test has any discriminatory value.
B	Test A has a total error rate of 5%.
C	Test B is better than test A at ruling in disease.
D	The PV+ for test A is 95%
E	Test A performs better than test B at discriminating the presence of disease

9- As the prevalence of a condition increases, a screening test for it will tend to have a

A	higher sensitivity.
B	higher specificity.
C	higher predictive value positive.
D	higher predictive value negative.
E	higher length biased sampling.

10- Which of the following measures of diagnostic test performance ideally has a small value?

A	Predictive value positive
B	Predictive value negative
C	Likelihood ratio for a positive test result
D	Likelihood ratio for a negative test result
E	None of the above

Answer 1

Question No. 1

Answer

B. An increase in specificity

• Screening test is used to confirm the presence of disease and also helps in planning for further treatment.
• Sensitivity refers to the ability of the test to identify patients with diseases correctly.
• Specificity refers to the ability of the test to recognize accurately those individual without the diseases.
• Sensitivity and specificity depends on the cut-off value above or below. Higher the screening test sensitivity and the lower the specificity and vice versa.
• If the cut-off point is higher – few false positives, more false negatives, highly specific, not very sensitive.
• If the cut-off point is lower – few false negatives, more false positives, highly sensitive, not very specific    .

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