A school physician examined a population of 1,500 school children in an attempt to detect heart disease. The prevalence of heart disease in this population is known to be 15%. The sensitivity of the physician’s examination is 60% and the specificity is 80%. All children who are labeled as "positive" by the school physician are sent for examination by a cardiologist. The sensitivity of the cardiologist’s examination is 70% ad its specificity is 90%. Hint: when doing your calculations to complete your 2x2 tables, round to the nearest whole number. Report sensitivity, specificity, positive predictive value and negative predictive value as percentages rounding to 1 decimal place. 1. How many children are labeled "positive" by the school physician? 2. What is the net sensitivity and net specificity of both examinations combined? 3. What is the positive predictive value of the cardiologist’s examination? 4. What is the positive predictive value of the school physician’s examination?