Deck 7: Diagnostic Statistics

Question 1

What does a lower negative ratio value tell you?

A) A lower negative ratio value is computed using 1-sensitivity.
B) A lower negative ratio value tells you the test is accurate because the true-negative rate will be greater than the false-negative rate.
C) A lower negative ratio value tells you that the test is inaccurate because the result misidentifies a large number of persons without the condition and identifies very few persons with a condition as having it.
D) A lower negative ratio value is used in diagnosing a condition or disease.

Answer 1

A lower negative ratio value tells you the test is accurate because the true-negative rate will be greater than the false-negative rate.

Question 2

Which is NOT true about positive predictive value?

A) The measure provides the percentage of true-positive scores in all persons with and without a condition who have a positive test result.
B) It is the probability a person with a positive test actually has a given condition.
C) The greater number of true-positive rates and fewer false-positive rates will result in a higher positive predictive value.
D) Clinically, you can use this percentage to predict the probability that a person has a condition if he or she tests positive.

Answer 2

The greater number of true-positive rates and fewer false-positive rates will result in a higher positive predictive value.

Question 3

In order to obtain the correct probability of a person having a condition, you need to consider three variables, including test sensitivity and test specificity. What is the third variable?

A) The prevalence of the condition
B) The positive predictive value
C) The negative predictive value
D) The likelihood ratio.

Answer 3

The prevalence of the condition

Question 4

Which is the term that means the percentage of persons who do have the attribute or disease who receive positive results?

A) Positive predictive value
B) False-positive score
C) True-positive score
D) True-positive rate

Question 5

What does a 0.85 sensitivity test value mean for chronic ankle instability?

A) It means that 85% of the patients with chronic ankle instability were identified as having balance impairments.
B) It means that 85% of subjects without chronic ankle instability were identified as not having balance impairments.
C) It means that 15% of the patients with chronic ankle instability were identified as having balance impairments.
D) It means that 15% of subjects without chronic ankle instability were identified as not having balance impairments.

Question 6

What does a 0.92 specificity test value mean for chronic ankle instability?

A) It means that 92% of the patients with chronic ankle instability were identified as having balance impairments.
B) It means that 92% of subjects without chronic ankle instability were identified as not having balance impairments.
C) It means that 8% of the patients with chronic ankle instability were identified as having balance impairments.
D) It means that 8% of subjects without chronic ankle instability were identified as not having balance impairments.

Question 7

Which is the formula for figuring out the sensitivity test value?

A) tP/ (tP + fP)
B) tP/ (tP + fN)
C) tN/ (fP + tN)
D) tN/ (fN + tN)

Question 8

Which is the formula for figuring out the specificity test value?

A) tP/ (tP + fP)
B) tN/ (fP + tN)
C) tP/ (tP + fN)
D) tN/ (fN + tN)

Question 9

What is true of the Youden index? Select all that apply.

A) The Youden index is computed by adding the sensitivity and specificity values, and then subtracting the number 1 with values ranging from 0 to 1.
B) The data point associated with a Youden index value closest to 100% is the optimal cutoff score.
C) The optimal cutoff score has the greatest accuracy and corresponds to the score with the greatest true-positive score and the lowest true-negative score.
D) The Youden index is the cutoff score at the most northwest point on the operating characteristic curve.

Question 10

What is true about the area under the curve? Select all that apply.

A) The area under the curve takes into consideration all the cutoff scores instead of one single data point.
B) The area under the curve provides the probability that the test result will positively identify a condition.
C) The area under the curve values range from 0% to 100%.
D) The area under the curve value of 59% is considered good because it is means the sensitivity and false-positive rate are greater than 50%.

Question 11

How does a receiver operating characteristic curve relate to the positive likelihood ratio? Select all that apply.

A) It plots all the data points related to comparison of the false-positive rate with the true-positive rate.
B) It plots all the data points related to comparison of the probability that a person has the attribute or disease will test positive with the probability that a person who does not have the attribute or disease will test negative.
C) It plots all the data points related to comparison of the 1-sensitivity rate with the true-positive rate.
D) It plots all the data points related to comparison of the 1-sensitivity rate with the 1-specificity rate.

Question 12

What is true of sensitivity and specificity? Select all that apply.

A) With sensitivity and specificity, you can estimate the probability of having a condition.
B) As sensitivity increases, specificity decreases.
C) The clinical application of sensitivity and specificity is for the most part limited to diagnostic purposes.
D) Sensitivity and specificity investigate the clinical usefulness of a test by determining the discriminate ability.

Question 13

Diagnostic Statistics for Balance Impairments with Chronic Ankle Instability
fN, false negative; fP, false positive; NLR, negative likelihood ratio; NPV, negative predictive value; PLR, positive likelihood ratio; PPV, positive predictive value; tN, true negative; tP, true positive.
According to the table, what is true of the negative post-test probability test value? Select all that apply.

A) The negative post-test probability that a person with a negative test result has chronic ankle instability is 14%.
B) The negative post-test probability that a person with a negative test result has chronic ankle instability is 86%.
C) The formula to calculate the negative post-test probability is tN/ (fN + tN).
D) The negative post-test probability is the probability of having the condition given a negative test result.

Question 14

What is true of exposed event risk and control event risk? Select all that apply.

A) These terms are used to indicate the risk of developing a given condition after receiving an exposure or intervention or not receiving an exposure or intervention.
B) The exposed event risk examines the percentage of subjects developing a condition following an intervention, thus dividing the number of event occurrences by the sum of event and nonevent occurrences in the intervention group.
C) The control event risk examines the percentage of subjects developing a given condition without an intervention.
D) The computation is identical to the exposed event risk, but the event risk is assessed in the intervention group.

Question 15

False-negative rate is 1-specificity.

Question 16

Sensitivity and specificity have an inverse relationship.

Question 17

When using diagnostic tests, you want tests with a high percentage of sensitivity and subjectivity.

Question 18

The major advantage to predictive values is you can transfer published predictive values between populations with different prevalence rates.

Question 19

Likelihood ratios have a distinct advantage over positive and negative predictive values in that this statistic transcends patient populations and allows clinical applicability to populations with different prevalence rates.

Question 20

Positive predictive value is computed as the percentage of true-positive scores in all persons with and without the condition who have positive test results.

Question 21

A lower negative ratio value tells you that the test is inaccurate because the result misidentifies a large number of persons without the condition and identifies very few persons with a condition as having it.

Question 22

High predictive values rule in a condition, whereas predictive values rule out a condition.

Question 23

Sensitivity is the true-positive test results divided by the sum of positive and negative test results for a condition.

Question 24

The true-negative rate is the clinical term for sensitivity.

Question 25

The major limitation to predictive values is that you cannot transfer predictive values between populations with different prevalence rates.

Question 26

A positive likelihood ratio value greater than 2 may be meaningful in diagnosing a condition, but you can feel confident that a clinical test result will rule in a condition as the value approaches and rises to more than 5.

Question 27

Statistically significant and meaningful area under the curve values will be between 0.80 to 1.00, unless there is a low number of subjects.

Question 28

With the Youden index, a value of 10 indicates a perfect test, and a value of 0 indicates a useless test.

Question 29

A receiving operating characteristic curve is a useful technique for determining appropriate cutoff scores that accurately distinguish between persons with and without a condition.

Question 30

Likelihood ratios transcend patient populations, thereby giving this statistic a distinct advantage over positive and negative predictive values.

Question 31

Perfect accuracy of a test is indicated by an area under the curve of 1.0, indicating that the sensitivity is 100% and the false-negative rate is 0%.

Question 32

The term that is defined as the percentage of persons who do not have the attribute or disease who receive negative test results is called ________________________.

Question 33

The term that is defined as the comparison of the true-positive rate with the false-positive rate is called ________________________.

Question 34

The term that is defined as the score that indicates the number of persons who actually have the condition but receive negative results on a clinical test is called _______________________.

Question 35

The notation used for the false-negative rate is ________________________.

Question 36

The value of each data point on a receiver operating characteristic curve that is used to determine the presence or absence of a condition is called _________________________.

Question 37

The term that is computed as 1 minus the value of the negative predictive value is called ________________________.

Question 38

The term that refers to an accuracy measure of a clinical test that takes into account all cutoff scores in your investigation and provides the probability that the test result will positively identify a condition is called ________________________.

Question 39

A graphic way to represent the positive likelihood ratio values for each point in a data set is called ______________________.

Question 40

To diagnose a condition, your first step is to know the cutoff score computed from a receiver operating characteristic curve analysis for determining a positive test result. Your second step in making a decision is to know the ________________________.