# When can a chi-squared distribution be used to analyze data?

##### 1 Answer

Jun 8, 2016

Chi Squared distributions can be used to describe statistical quantities which are a function of a sum of squares.

#### Explanation:

The Chi Squared distribution is the distribution of a value which is the sum of squares of

The PDF of the Chi Squared distribution is given by:

Where

The usefulness of the Chi Squared distribution is in modelling things which involve the sums of squared values. Two specific examples are:

- Analysis of Variance tests (variance is a sum of squared values)
- Goodness of fit (for a least squares fit where the error is a sum of squared values)

Taken from:

https://en.wikipedia.org/wiki/Chi-squared_distribution