Remark: Because z-scores are unitless, we can use z-scores to compare observations from different distributions.

Example: US newborns have a mean birth weight of 3250g with a

standard deviation of 550g. Babies born in Japan have a mean birth weight of 2980g with a standard deviation of 400g. A baby born to a US mother weighed 4000g. A baby born to a Japanese woman weighed 3600g. Which baby is larger relative to its population?