What are Degrees of Freedom in Statistics

Understanding degrees of freedom in statistics: definition, explanation, and meaning

What are Degrees of Freedom in Statistics?

Degrees of freedom is a fundamental concept in statistics that often goes unnoticed but plays a significant role in various statistical tests. It is a term that describes the number of values in a statistical calculation that are free to vary. In simpler terms, degrees of freedom are the number of independent pieces of information that go into the calculation of a statistic.

Understanding Degrees of Freedom

To understand the concept of degrees of freedom, consider a simple example. Suppose you have three numbers that have an average (mean) of 10. If you know the first two numbers, you can easily calculate the third number because it is not free to vary. In this case, you have two degrees of freedom because only the first two numbers can vary freely.

Importance of Degrees of Freedom

The concept of degrees of freedom is crucial in statistics because it impacts the shape of various statistical distributions such as the t-distribution and the chi-square distribution. The number of degrees of freedom can alter the shape of these distributions, which in turn affects the outcome of hypothesis tests and the construction of confidence intervals.

How are Degrees of Freedom Used in Statistics?

Degrees of freedom are used in several statistical tests, including the t-test, chi-square test, and ANOVA (Analysis of Variance). These tests use degrees of freedom to determine the critical values, which are used to decide whether to reject the null hypothesis.

Application in T-Test

In a t-test, the degrees of freedom are calculated as the total number of observations minus one (N-1). This is because one parameter (the mean) is estimated from the data. The calculated t-value is then compared with the critical t-value from the t-distribution table with the corresponding degrees of freedom to determine the test outcome.

Application in Chi-Square Test

In a chi-square test, the degrees of freedom are calculated as the number of categories minus one. The calculated chi-square value is then compared with the critical chi-square value from the chi-square distribution table with the corresponding degrees of freedom.

Application in ANOVA

In ANOVA, the degrees of freedom are a bit more complex. They are calculated separately for the between-group variability (k-1, where k is the number of groups) and the within-group variability (N-k, where N is the total number of observations). The F-statistic is then calculated using these degrees of freedom, and compared with the critical F-value from the F-distribution table.


In summary, degrees of freedom is a crucial concept in statistics that describes the number of values that are free to vary in a statistical calculation. It plays a significant role in various statistical tests, affecting the shape of statistical distributions and the outcome of hypothesis tests. Understanding this concept can help in the correct application and interpretation of statistical tests.


TradingChooser is the premier website for comparing the top online brokers. Developed by experts and trading enthusiasts, its primary objective is to provide traders with essential information regarding the most renowned online trading platforms.

Risk Disclaimer

Trading CFDs and forex involves highly speculative products that carry a significant risk of capital loss. Investments in financial products are susceptible to market risks. Certain financial instruments, including cryptocurrencies, are particularly speculative, and any investment should be made using funds designated as 'risk capital'. Previous market performance does not guarantee future outcomes.

Our stock market recommendations are sourced from what we consider reliable sources; however, we cannot guarantee their complete accuracy or truthfulness. They are provided solely for informational purposes and should not be construed as an invitation or solicitation to invest.

Advertiser Disclosure

TradingChooser provides global traders with a comprehensive platform to access in-depth information about various trading brokers. We meticulously examine company profiles and conduct daily investigations to identify potential frauds or scams in the industry. The trading brokers mentioned above undergo thorough verification and analysis by our team of experts, who consider the key features that a trading platform should possess.