SUPP 5.1. One biomarker in the study of bone density is tartrate resistant acid phosphatase (TRAP) in unit/liter of blood. For 31 young women, the sample average TARP was 13.2 U/L. The population standard deviation, sigma, is known to be 6.5 U/L.

a) Find the standard error. Explain the relationship between the standard deviation and the standard error so that a nonstatistician could understand.

b) Find the margin of error. Explain the relationship between the standard error and the margin of error.

c) A new follow-up study was to be conducted. Find the sample size required to provide an estimate of the average TRAP with a margin of error of 1.5 U/L with 95% confidence.