Deck 3: Clinical Evaluation of Methods

Question 1

ROC curves are most useful in assessing the performance of quantitative laboratory analyses because:

A) multiple tests for the same analyte can be evaluated at one time.
B) they can display performance of tests over the entire range of decision values.
C) they allow specific reference intervals to be determined for each analysis.
D) they can evaluate combination testing in a single plot.

Answer 1

they can display performance of tests over the entire range of decision values.

Question 2

A receiver operating characteristic (ROC)curve is a plot of:

A) systematic error against random error.
B) tumor marker decision levels versus upper limit of reference intervals.
C) true positives versus false positives.
D) specificity of one method against the specificity of another method.

Answer 2

true positives versus false positives.

Question 3

In regard to the number of true-positive and negative,and false-positive and negative,results in laboratory testing,the prevalence times the sensitivity is equal to the number of:

A) true positives.
B) false positives.
C) true negatives.
D) false negatives.

Answer 3

true positives.

Question 4

Calculate the sensitivity for the following data: in a group of 80 patients diagnosed with sickle cell disease,72 tested positively for it.The sensitivity of this test is:

A) 111%.
B) 100%.
C) 90%.
D) 75%.

Question 5

To calculate the sensitivity of a laboratory test to correctly classify true positives,one must first know the number of:

A) true positives and false negatives.
B) true negatives and false positives.
C) true positives and false positives.
D) false positives and false negatives.

Question 6

A method that can be used to calculate the probability of a disease after new information is added to previously obtained information involves:

A) likelihood analysis.
B) sensitivity analysis.
C) Bayes theorem.
D) combination testing.

Question 7

True negatives ÷ (false positives + true negatives)is the formula for determining:

A) sensitivity.
B) specificity.
C) the odds ratio.
D) the likelihood ratio.

Question 8

Combination testing involves the use of multiple laboratory tests in an attempt to decrease costs or assist in diagnosing a specific disease.One of the problems with this type of testing is that:

A) false-positive results increase.
B) true-negative results increase.
C) the prevalence of the disease increases.
D) the predictive value of a negative test increases.

Question 9

A laboratory analysis that produces quantitative results with an infinite number of sensitivity and specificity pairs is referred to as a _____ test.

A) predictive
B) qualitative
C) dichotomous
D) continuous

Question 10

In regard to clinical evaluation of method,a high clinical sensitivity means few false negatives.

Question 11

To calculate the predictive value of a positive test,which of the following should be known?

A) Sensitivity only
B) Specificity and prevalence only
C) Sensitivity and specificity only
D) Sensitivity,specificity,and prevalence

Question 12

The probability of occurrence of a specific test value given that the disease is present divided by the probability of the same test value if the disease was absent is the:

A) odds ratio.
B) likelihood ratio.
C) prevalence.
D) predictive value.

Question 13

Nondiseased individuals that are classified as diseased by having a positive result on a specific laboratory test are considered:

A) true positives.
B) false positives.
C) true negatives.
D) false negatives.

Question 14

The proportion of a population that has the particular disease being studied is referred to as the:

A) prevalence.
B) predictive value.
C) positive value.
D) clinical sensitivity.

Question 15

What is the positive predictive value of a test in which 220 tested individuals with positive test results actually have the disease and 45 tested individuals with positive test results do not have the disease?

A) 16.9%
B) 66%
C) 83%
D) 120%