The nuchal translucency test is a special ultrasound scan which is widely used as a screeding test for Down's syndrome in early pregnancy. The test measures the uid under the skin at the back of the baby's neck and can be used to determine the risk of having a baby with Down's syndrome. The following table gives the test results for a sample of 1,000 pregnant women, with the age between 35 and 40:
Down syndrome baby Normal baby Total
Test + 3 50 53
Test - 2 945 947
Total 5 995 1,000
Calculate
(a) The false positive rate and false negative rate of the test,
(b) The sensitivity and specicity of the test,
(c) The positive predictive value and negative predictive value of the test.