DEFINITION of 'Mean'
The simple mathematical average of a set of two or more numbers. The mean for a given set of numbers can be computed in more than one way, including the arithmetic mean method, which uses the sum of the numbers in the series, and the geometric mean method. However, all of the primary methods for computing a simple average of a normal number series produce the same approximate result most of the time.
INVESTOPEDIA EXPLAINS 'Mean'
If stock XYZ closed at $50, $51 and $54 over the past three days, the arithmetic mean would be the sum of those numbers divided by three, which is $51.67.
In contrast, the geometric mean would be computed as third root of the numbers' product, or the third root of 137,700, which approximately equals $51.64. While the two numbers are not exactly equal, most people consider arithmetic and geometric means to be equivalent for everyday purposes.
VIDEO

Moving Average  MA
A widely used indicator in technical analysis that helps smooth ... 
Variance
The spread between numbers in a data set, measuring Variance ... 
Standard Deviation
1. A measure of the dispersion of a set of data from its mean. ... 
Mean Reversion
A theory suggesting that prices and returns eventually move back ... 
Arithmetic Mean
A mathematical representation of the typical value of a series ... 
Coefficient Of Variation  CV
A statistical measure of the dispersion of data points in a data ...

What is the difference between standard deviation and mean?
Understanding the calculation and interpretation of mathematical fundamentals such as mean and standard deviation is essential ... Read Full Answer >>

Active Trading Fundamentals
Weighted Moving Averages: The Basics
We take a closer look at the linearly weighted moving average and the exponentially smoothed moving average. 
Personal Finance
2 Years Of Education, A Lifetime Of Success
Believe it or not, many twoyear colleges have advantages over their fouryear counterparts. 
Fundamental Analysis
What is a Null Hypothesis?
In statistics, a null hypothesis is assumed true until proven otherwise. 
Investing
How to Use Stratified Random Sampling
Stratified random sampling is a technique best used with a sample population easily broken into distinct subgroups. Samples are then taken from each subgroup based on the ratio of the subgroup’s ... 
Fundamental Analysis
Lognormal and Normal Distribution
When and why do you use lognormal distribution or normal distribution for analyzing securities? Lognormal for stocks, normal for portfolio returns. 
Investing Basics
Using Normal Distribution Formula To Optimize Your Portfolio
Normal or bell curve distribution can be used in portfolio theory to help portfolio managers maximize return and minimize risk. 
Technical Indicators
The Normal Distribution Table, Explained
The normal distribution formula is based on two simple parameters  mean and standard deviation 
Economics
Can Investors Trust Official Statistics?
The official statistics in some countries need to be taken with a grain of salt. Find out why you should be skeptical. 
Investing Basics
RSquared
Learn more about this statistical measurement used to represent movement between a security and its benchmark. 
Active Trading Fundamentals
Hypothesis Testing in Finance: Concept & Examples
When you're indecisive about an investment, the best way to keep a cool head might be test various hypotheses using the most relevant statistics.