Sentence:  Recall the exercise at the end of the previous chapter, and imagine that you discover just one <WSD>Antarctican</WSD>, and you measure his or her body temperature. If you know the population mean for <WSD>Antarcticans</WSD> (perhaps it is 98.6&deg;F), then you have one piece of information about variability. 
Meaning of the word marked with <WSD> tags:  A native of Antarctica.