Question 2: What is meant by 95% CI 6.1 to 8.8%?
This is the 95% confidence interval. It is a range of values which we estimate will contain the population percentage of preterm births. This is in the sense that if a large number of samples were taken from the same population, then 95% of the calculated confidence intervals would contain the population percentage. Here we can deduce that the population value is very likely to lie between 6.1% and 8.8%.
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Last updated: 27 July, 2009.