A medical research team wishes to evaluate a proposed screening test for Alzheim

Question

A medical research team wishes to evaluate a proposed screening test for Alzheimer's disease. The test was given to a random sample of 450 patients with Alzheimer's disease and an independent random sample of 500 patients without symptoms of the disease. The two samples were drawn from populations of subjects who were 65 years of age or older. The table below shows the results.

1. Calculate the probability of false positive and false negative.

2. Compute the predictive value of the test (PPV). This means the probability that an individual will have the disease given they test positive or P (Alzheimer's/test is positive).

Explanation / Answer

a)here probability of false positive=test result posiitve given no Alzheimer disease =5/(495+5)=5/500=0.01

false negative =test negative given  Alzheimer disease =14/(436+14)=0.0311

2)

PPV =number of true positive/(number of true positive+number of false posiitve)=436/(436+5)=0.9887

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