Benedictine University MPH604 Week 3 Quiz

Week 3 Quiz Answers

 

1.         A screening test for a newly discovered disease is being evaluated for its performance as a screening test. In order to determine the effectiveness of the new test, it was administered to 270 workers. A total of 42 individuals who had been diagnosed with the disease tested positive for it. Results showed a negative test for an additional 25 people with the disease. A total of 51 people without the disease tested positive. What is the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the test? Please match the measures to their correct answers below.

 

62.7% - Sensitivity

85.9%-  Negative Predictive Value

74.9%- Specificity

45.2%- Positive Predictive Value

37.3%- None of these

71.9%-Accuracy

54.8%-None of these

14.1%-None of these

 

Calculation:

 

a)         What is the prevalence rate of the disease?

b)         What is the sensitivity of the test?

c)         What is the specificity of the test?

d)         What is the positive predictive value of the test?

e)         What is the negative predictive value of the test?

f)          What is the accuracy of the test?

 

2.         A screening test wished to improve the diagnostic ability to identify Zika-infected fetuses in pregnancy rather than after birth. A total of 330 pregnant women (carrying one baby each) in Miami were tested.A total of 36 babies had Zika; 24 of whom tested positive. A total of 300 babies tested negative for the virus. What is the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the test? Please match the measures to their correct answers below.

 

                  20.0% - None of these

                     94.5%- Accuracy

                   82.6% - None of these

                  33.3% - None of these

                  66.7% - Sensitivity

                  96.0%- Negative Predictive Value

                    98.0% - Specificity

                 80.0% - Positive Predictive Value

 

Calculation:

 

a)         What is the prevalence rate of disease?

b)         What is the sensitivity of the test?

c)         What is the specificity of the test?

d)         What is the positive predictive value of the test?

e)         What is the negative predictive value of the test?

f)          What is the accuracy of the test?

 

3.         What are the characteristics of a good screening test? Please select all that apply.

 

Select one or more:

a)         Expensive - high cost-benefit ratio

b)         Acceptable - socially acceptable to the target group

c)         Simple - easy to learn and to perform

d)         Rapid - quick to administer and provide results

e)         Multi-platform - available in several forms, including online, in the field, and over the phone

f)          Safe - minimal harm to the participant

 

4.         What is "reliability" in a study? Please select all that apply.

 

Select one or more:

a)         Degree to which different test givers or interviewers rate the same person or test the same way given proper training

b)         Degree to which questions in a survey agree with one another when measuring the same attribute or variable

c)         Can only be evaluated if a "Gold Standard" exists

d)         Ability of the test to get the true value

e)         Also known as accuracy

f)          Ability of a test to get the same result over and over again

 

 

5.         What is "validity" in a study? Please select all that apply.

 

Select one or more:

a)         Degree to which different test givers or interviewers rate the same person or test the same way given proper training

b)         Degree to which questions in a survey agree with one another when measuring the same attribute or variable

c)         Can only be evaluated if a "Gold Standard" exists

d)         Ability of the test to get the true value

e)         Also known as accuracy

f)          Ability of a test to get the same result over and over again

 

6.         Match each term with its corresponding definition.

1)         The proportion of those who do not have the disease who test negative.-

2)         The proportion of those who test positive who actually have the disease.-

3)         The proportion of those who have the disease who test positive.-

4)         The proportion of those who test negative who actually do not have the disease.-

7.         The prevalence of disease in a population affects the positive predictive value of a screening test, and thus, the prevalence of the disease should be known to interpret the performance of a screening test.

 

Select one:

 

a.         True

b.         False

 

 

8.         The image describes a hypothetical distribution of blood glucose concentrations in patients with and without diabetes. What point is represented by Z?

 

Select one:

a. The point at which sensitivity is maximized

b. The point at which specificity is maximized

c. The point at which the trade-off between sensitivity and specificity is minimized

9.         A cross-sectional study is an appropriate study design to avoid lead time and length biases when evaluating screening programs.

Select one:

 

a.         True

b.         False

 

10.Please match the terms below with their definitions.

 

This bias may make it look like participants who receive an early diagnosis live longer with the disease than those who receive a later diagnosis, when in fact, this may not be true. -?

This bias may make it look like participants who are screened have better health outcomes than those who are not based on the characteristics of individuals who participate in screening programs.-->

This bias may make it look like cases of disease that are identified in screening programs have better outcomes than those identified after becoming symptomatic, when in fact, cases identified via screening may inherently have better prognoses than those not identified via screening.

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