DEFINITION of 'T Distribution'
A type of probability distribution that is theoretical and resembles a normal distribution. A T distribution differs from the normal distribution by its degrees of freedom. The higher the degrees of freedom, the closer that distribution will resemble a standard normal distribution with a mean of 0, and a standard deviation of 1.
The T distribution is also known as the "Student's T Distribution".
INVESTOPEDIA EXPLAINS 'T Distribution'
The use of a T distribution is precluded by the standard deviation of the population parameter being unknown and allows the analyst to approximate probabilities, based on the mean of the sample, the population, the standard deviation of the sample and the sample's degrees of freedom. As the sample's degrees of freedom approaches 50, the T distribution will virtually be identical to the normal distribution.

Degrees Of Freedom
In statistics, the number of values in a study that are free ... 
Acceptance Sampling
A statistical measure used in quality control. A company cannot ... 
Nonparametric Statistics
A statistical method wherein the data is not required to fit ... 
Standard Deviation
1. A measure of the dispersion of a set of data from its mean. ... 
Probability Distribution
A statistical function that describes all the possible values ... 
NonSampling Error
A statistical error caused by human error to which a specific ...

Personal Finance
Does Your Investment Manager Measure Up?
These key stats will reveal whether your advisor is a league leader or a benchwarmer. 
Mutual Funds & ETFs
5 Ways To Measure Mutual Fund Risk
These statistical measurements highlight how to mitigate risk and increase rewards. 
Bonds & Fixed Income
Find The Highest Returns With The Sharpe Ratio
Learn how to follow the efficient frontier to increase your chances of successful investing. 
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 ... 
Economics
How A Limited Government Affects A Country's Finances
Countries with limited governments have fewer laws about what individuals and businesses can and can’t do. What's the net result? 
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
How Does Goodwill Affect Financial Statements?
Goodwill is a bit of a paradoxintangible, yet it is recorded as an asset on the purchasing company's balance sheet. 
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.