Deck 12: Method Evaluation

Question 1

A positive result for a patient who does not actually have the condition is considered to be a

A) false negative.
B) false positive.
C) true negative.
D) true positive.

Answer 1

false positive.

Question 2

When discussing a diagnostic test,what does sensitivity refer to?

A) The ability of a diagnostic test to detect only the medical condition in question
B) The ability of a diagnostic test to detect the medical condition in question in every patient who has the condition
C) The frequency of the condition in the population tested at a given time
D) The quantity that tells the probability that a result from a diagnostic test is correct

Answer 2

The ability of a diagnostic test to detect the medical condition in question in every patient who has the condition

Question 3

How is bias determined?

A) Calculate the difference from any outlier data points to the mean.
B) Compare the average result from several dozen samples to known referent values.
C) Plot the results of several dozen samples as a standard curve and compare them to the referent values provided by the manufacturer.
D) Subtract the mean result from the reference method from the mean result of the new method.

Answer 3

Subtract the mean result from the reference method from the mean result of the new method.

Question 4

Which of the following variables has a significant effect on the predictive value of a test?

A) The doctor diagnosing the condition
B) The prevalence of the condition
C) The severity of the condition
D) The volume of the patient's sample tested

Question 5

How is the reportable range of an assay determined?

A) By calculating the standard deviation of known concentrations
B) By comparing the referent value to the number of false positives and false negatives
C) By establishing the nonparametric ranking of the data and using the lowest and highest points
D) By testing several specimens of known concentration that span the analytical range

Question 6

The positive predictive value of a test is 92%.What does this tell us?

A) The condition is actually present in 92 out of every 100 people who test positive.
B) The condition is present in 92 out of every 100 people with similar demographic and clinical characteristics.
C) The test will give a negative result in 92 out of every 100 patients who do not have the condition.
D) The test will provide a correct result 92 of every 100 times.

Question 7

What does a recovery experiment test for?

A) Cholesterol concentrations
B) Interference
C) Proportional systematic error
D) Validity

Question 8

How is the reference rage of an assay determined?

A) By testing 100-150 known standards and determining the range that runs from the lowest value to the highest value
B) By testing 100-150 specimens that represent the laboratory's patient population and determining the range that runs from 2 SD below the mean to 2 SD above the mean
C) By testing 100-150 specimens that represent the laboratory's patient population and ordering the values from lowest to highest with the lowest and highest values representing the range
D) None of the above

Question 9

If there were no false positives,what would the specificity of a diagnostic test be?

A) 0%
B) 25%
C) 50%
D) 100%

Question 10

How is the precision of a new method compared to the precision of the current method?

A) By calculating the standard deviation from the mean
B) By creating a double-blind study
C) By using an F test
D) By using a Student's t test

Question 11

In the context of diagnostic tests,what does "specificity" refer to?

A) The ability of a diagnostic test to detect only the medical condition in question
B) The ability of a diagnostic test to detect the medical condition in question in every patient who has the condition
C) The frequency of the condition in the population tested at a given time
D) The quantity that tells the probability that a result from a diagnostic test is correct

Question 12

What is the common approach for determining the accuracy of a method or instrument?

A) Compare the results from several dozen samples obtained by the method under evaluation with the results obtained by an established reference method.
B) Create a standard curve from the results of several dozen samples and compare all future test results to the standard curve.
C) Test several dozen samples, average the results, and compare the average to the referent values suggested by the manufacturer.
D) All of the above

Question 13

When testing for medical conditions,when is a high efficiency most desired?

A) When only a false positive might cause harm
B) When the condition is both serious and treatable, and a false positive and false negative are equally injurious
C) When the suspected medical condition is serious but not treatable, and a false positive can cause harm
D) When the suspected medical condition is serious and treatable, and a false positive does not have harmful consequences

Question 14

When testing for medical conditions,when is high specificity most desired?

A) When a false positive might cause harm
B) When the condition is both serious and treatable, and a false positive and false negative are equally injurious
C) When the suspected medical condition is serious but not treatable, and a false positive can cause harm
D) When the suspected medical condition is serious and treatable, and a false positive does not have harmful consequences

Question 15

What does it mean that an assay is said to be "linear"?

A) The final result for a given analyte is directly proportional to the analyte's true measure in the specimen.
B) The lowest and highest results for an assay are accurate when compared to known standards.
C) The reference range for an assay provides true positive results for greater than 98% of patients.
D) There is no interfering substance obscuring the results.

Question 16

The efficiency of a diagnostic test is determined to be 92%.What does this say about the test?

A) A positive result from the diagnostic test is correct 92 out of every 100 tests.
B) The condition is present in 92 out of every 100 people with similar demographic and clinical characteristics.
C) The test will give a negative result in 92 out of every 100 patients who do not have the condition.
D) Out of every 100 test results, 92 are correct.

Question 17

The prevalence of a diagnostic test is determined to be 92%.What does this information tell us?

A) A positive result from the diagnostic test is correct 92 out of every 100 tests.
B) The condition is present in 92 out of every 100 people with similar demographic and clinical characteristics.
C) The test will give a negative result in 92 out of every 100 patients who do not have the condition.
D) The test will provide a correct result 92 of every 100 times.

Question 18

In the context of diagnostic tests,what does "prevalence" refer to?

A) The ability of a diagnostic test to detect only the medical condition in question
B) The ability of a diagnostic test to detect the medical condition in question in every patient who has the condition
C) The frequency of the condition in the population tested at a given time
D) The quantity that tells the probability that a result from a diagnostic test is correct

Question 19

The sensitivity of a diagnostic test is determined to be 92%.What does this say about the test?

A) A positive result from the diagnostic test is correct 92 out of every 100 tests.
B) The condition is present in 92 out of every 100 people with similar demographic and clinical characteristics.
C) The test will detect the condition in 92 out of every 100 patients who have the condition.
D) The test will give a negative result in 92 out of every 100 patients who do not have the condition.

Question 20

What is a difficulty in relying on referent values or cutoffs in converting a numerical test results into a yes-or-no clinical diagnosis?

A) Test results can fall beyond the cutoff values, leaving the diagnostic question unanswered.
B) The cutoff value is patient-specific and must be calculated for each individual patient.
C) The value considered to be the cutoff is variable depending on the prescribing physician.
D) There is a range of test result values that are shared between those with and without the condition.