Chapter 5 HW

Chapter 5 HW - Therefore, the disease must be more...

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Chapter 5 HW Sojung Suk 7/6/2009 Biopsy-proven adenocarcinoma of the breast Total Physical Examination Yes No Exam (+) Positive 1800 800 2600 Exam (-) Negative 700 4200 4900 Total 2500 5000 7500 1. The sensitivity of the physical examination was: Persons with disease (True positives +False negatives) =1,800 = 0.720 or 72.0% 2,500 2. The specificity of the physical examination was: Persons without disease (True negatives +False positives) =4,200 = 0.840 or 84.0 % 5,000 3. The positive predictive value of the physical examination was: Persons with test positive (True positives +False positives) =1,800 = 0.692 or 69.2% 2,600 4. The best answer is d PPV=TP/(TP+FP),
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Chap te r 5 HW So jung Suk 7 /6 /2009 TP/(TP+FP) +FP/(TP+FP)=(TP+FP)/(TP+FP)=1 Therefore, FP/(TP+FP)=1- TP/(TP+FP) =1-PPV And 1-PPV of population A <1-PPV of population B then, PPV of population A>PPV of population B
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Unformatted text preview: Therefore, the disease must be more prevalent in population A As the disease prevalence increase, the true positive numbers increase and then, the positive predictive value increases, too. Therefore, the disease must be more prevalent in population A 5. The best answer is d the audiometric test is more sensitive (sensitivity is greater) and less specific (specificity is smaller) based on the calculation below Sensitivity of physical examination =240/300=0.0800 or 80.0% Specificity of the physical examination =160/200=0.800 or 80% PHYSICAL EXAMINATION Total RESULT PROBLEMS PRESENT PROBLEMS ABSENT Positive 240 40 280 Negative 60 160 220 Total 300 200 500 Sensitivity of audiometric test =270/300 =0.900 or 90.0 % Specificity of audiometric test =140/200 =0.700 or 70.0 % AUDIOMETRIC TEST Total RESULT PROBLEMS PRESENT PROBLEMS ABSENT Positive 270 60 330 Negative 30 140 170 Total 300 200 500...
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Chapter 5 HW - Therefore, the disease must be more...

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