Scenario 2: To observe the effect of increasing sensitivity, assume a blood sugar screening level of 130 mg/dl, with (A) sensitivity of 44.3% and (D) specificity of 99.0%.Use the values for a + c from the table below to calculate prevalence.

Questions 15-23: Using the information in the Week 3 PPT, set up a two by two table with the appropriate numbers in each cell of the table.Round to the nearest whole number, but only after you have completed all the calculations down through.(Condition Absent or Present is determined by symptoms.) (1 point per box)

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Ills

Wells

Total people

Positive tests

(A or True +)

(B or False +)

(A+B or all positive tests)

Negative tests

(C or False -)

(D or True -)

(C+D or all negative tests)

Total tests

(A+C or all ills)

(B+D or all wells)

10,000

Total Population

Calculate as indicated

Answer (2 pts. each)

Points

24.The percentage of false positives among all those without the condition (the Type I Error Rate, or 1 - specificity), or b / (b + d)

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25. The percentage of false negatives among all those with the condition (the Type II Error Rate, or 1 - sensitivity), or c / (a + c)

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26.The predictive value of a positive (PPV) test,

or = a / (a + b)

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27. The predictive value of a negative (NPV) test,

or d / (c + d)

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28.Based on the calculations above, how many false positives (b x 10) and negatives (c x 10) will occur if 100,000 people are screened?

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Select a laboratory test and describe its:

Answer (6 points each)

Points

29. Explain the clinical significance of a diagnostic test's sensitivity and specificity. Be specific in your explanation by using a diagnostic test as an example.

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30.Compare the findings of Scenario 1 and 2.If you were the director for the diabetes screening program would you prefer to screen at 130 mg or 180 mg percent? Explain why. (6 pts.)

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