<PRE><B>Question 219164</B>
Jolly Blu Gaint Health Insurance (JBGAI) is concerned about rising lab test costs and would like to know what roportion of the positive lab test for prostate cancer are actually proven correct through subsequent biopsy. JBGAI demands a sample large enough to ensure an error of =+ 25% with 90% confidence. what is the necessary sample size?
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invNorm(0.05) = 1.645
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E = z*sqrt(pq/n)
n = [z/E]^2[pq]
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n = [1.645/0.25]^2[0.5*0.5]
n = 10.82
Rounding up:
n = 11
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Cheers,
Stan H.</PRE>