Standard deviations are important here because the shape of a normal curve is determined by its mean and standard deviation. The mean tells you where the middle, highest part of the curve should go.

Standard deviation is a measurement of market volatility. Learn how investors use standard deviation in the MoneySense Glossary.

The equation for the standard error of the mean is the sample standard deviation divided by the square root of the sample size.

Determination There are several practical ways to calculate the mean and standard deviation. Scientific calculators typically come with a built-in program for both the mean and standard deviation.