Most things in nature form a Gaussian curve. That is to say when you are talking about the height of men or the weight of babies, most of the values are clustered around the average value, and only 5% are more than two standard deviations above or below the mean (a standard deviation can be thought of as the typical amount individuals deviate from the mean). By taking a poll of the height of men at Daily Kos, I hope to get a Gaussian curve (next diary I will take a poll of women's heights).