Standard Deviation

Definition

Standard Deviation in plain English

Standard deviation is one number that tells you how spread out a bunch of data is, are the values all clustered close together, or scattered far apart? You find the average (the mean), see how far each value sits from that average, and combine those distances into a typical 'gap' size. Imagine two classes with the same average test score of 80: in one, everyone scored between 78 and 82 (small standard deviation, very consistent), while in the other scores ranged from 50 to 100 (large standard deviation, all over the place). A bigger standard deviation means more variety; a smaller one means the data huddles near the average.

Learn these first

• Absolute Value
• Arithmetic Mean

Related GMAT terms

• Absolute Value
• Arithmetic Mean
• Composite Number
• Discrete Data
• Discriminant
• Domain
• Exponent
• Factorial
• Greatest Common Divisor (GCD)
• Independent Events