Measles. Health researchers at a large HMO base their cost predictions for measles on the belief that 98% of children have been vaccinated against measles. A random survey of medical records at many schools across the country found that, among more than 13,000 children, only 97.4% had been vaccinated. A statistician would reject the 98% hypothesis with a P-value of P 6 0.0001.

a) Explain what the P-value means in this context.

b) The result is statistically significant, but is it important?

Comment.