# Statistics - Deviation Score (for one observation)

The deviation score is the difference between two scores as :

• a value $X$
• and an other value (usually the predicted score: mean, …)

## Example

• the mean $\bar{X}$ of a distribution for the calculation of the correlation coefficient
• or a predicted variable for the calculation of a regression coefficient

## Deviation Form

By putting all scores of a variable in a deviation form, the average for this variable will be equal to zero. It's called centering.

To center means to put in deviation form.