S0018 [Source: Edwards & Baird (2005). Medsurg Nursing 14(4):220-230.]

Test results in older adults may have different meanings from those in younger individuals. The table below shows the reference ranges for some laboratory tests. Note that reference ranges are those intervals within which 95% of the values fall for a specific population.

**Questions:**

Q1. Given a random sample of adults, what percentage of them would you expect whose ferritin values fall within their reported reference ranges.

Q2. There can be at least two ways to obtain a reference range for a laboratory test from a given random sample of values. What are they?

Q3. Compare the two methods you described in Q2. How would you choose between the two methods?

Q4. What is the difference between a reference range and a 95% confidence interval?