7. Investigators want to assess the accuracy of self-reported smoking status. Pa

Question

7. Investigators want to assess the accuracy of self-reported smoking status. Participants are asked whether they currently smoke or not. In addition, laboratory tests are performed on hair samples to determine the presence or absence of nicotine. The laboratory assessment is considered the truth about nicotine. Use the data in the following table to answer the questions. Hint: Be careful of how the cells are arranged.

Nicotine Absent

Nicotine Present

Self-Reported Non-Smoker

82

32

Self-Reported Smoker

3

97

a. What is the sensitivity of self-reported smoking status?

b. What is the specificity of self-reported smoking status?

c. What is the positive predictive value of the laboratory assessment?

Nicotine Absent

Nicotine Present

Self-Reported Non-Smoker

82

32

Self-Reported Smoker

3

97

Explanation / Answer

(a) Sensitivity = True Positive / (True positive + False Negative)

= 97 / (97+3)

= 97%

(b) Specificity = True Negative / (True negative + false positive)

= 82 / (82+32)

= 28.07%

(c) Positive Predictive Value = 97 / (97+82)

= 54.19%

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