A theoretical data distribution which appears bell shaped, is symmetrical about the mean and has the most probable scores concentrated around the mean. Progressively less likely scores occur further away from the mean. 68.26% of the scores lie within one standard deviation either side of the mean, 95.44% of the scores lie within 2 standard deviations either side of the mean and 99.75% fall within three standard deviations.
The exact shape of the bell curve is determined by the standard deviation. The mean and median are at the same point. Also called: Gaussian distribution or a bell curve.
Even though a moment’s thought reveals that nice, normal distribution is terribly worrisome on this island.
Michael Crichton -- Jurassic Park
Also, they should follow the same old normal distribution curve, the bulk of them in the middle, a few morons on one end, a few geniuses on the other.
Roger Zelazny -- My Name is Legion
So I pushed my mind around inside the parameters she had laid down, and one of the things that came to me was Barthelme’s mention of the normal distribution curve with reference to dolphins.