This article describes how to perform a Barlett Test of Sphericity. This test is used to make sure that the correlation matrix of the variables in your dataset diverges significantly from the identity matrix. An identity matrix is a matrix in which all of the values along the diagonal are 1 and all of the other values are 0. If the p-value from Bartlett’s Test of Sphericity is lower than your chosen significance level (common choices are 0.10, 0.05, and 0.01), then we can assume that the variables in the correlation matrix are not orthogonal.

## Requirements

A Displayr document containing a data set which contains two or more variables which have a **Structure** set as **Numeric** or **Numeric-Multi**. Note that binary variables can also be used as inputs but will be converted to numeric when calculating the correlation coefficients. If you use categorical or ordinal variables, they will be coerced to numeric based on their values for the purposes of running the test.

## Method

- Select
**Anything > Advanced Analysis > Test > Barlett Test of Sphericity**. -
**In the object inspector**, specify the variables to use under**Inputs > Input Variables.** - OPTIONAL: Select
**Missing data**to change the way missing values are handled- Select
**Use partial data (pairwise correlations)**to treat each pair of variables separately and only include observations that have valid values for each pair in the data set. - Select
**Error if missing data**if you do not want the test performed if there is any missing data - Select
**Exclude cases with missing data**if you only want to use cases with valid values on all the variables - Select
**Imputation (replace missing values with estimate)**to request that imputation techniques be used to replace missing values with estimates

- Select
- OPTIONAL: Select
**Variable names**to display variable names in the output instead of the variable labels - OPTIONAL: Select
**More decimal places**to display numeric values with 8 decimal places.

## Next

How to do a principal components analysis in Displayr