In August 1976, tuberculosis was diagnosed in a high school student (INDEX CASE) in Corinth, Mississippi. Subsequently, laboratory studies revealed that the student's disease was caused by drug-resistant tubercule bacilli. An epidemiologic investigation was conducted at the high school. Table E4.6 gives the rates of positive tuberculin reaction, determined for various groups of students according to degree of expo-sure to the index case. Calculate the 95% confidence interval for the rate of positive tuberculin reaction separately for each of the two subpopula- tions, those with high exposure and those with low exposure.
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TABLE E4.6
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Exposure Level
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Number Tested
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Number Positive
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High
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129
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63
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Low
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325
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36
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