Coding is a way of simplifying data. Each value is converted using a formula to produce a new set of values which are easier to work with.

If the data are coded using the formula $y = \dfrac{x-a}{b}$,

then the mean is given by $\bar{y} = \dfrac{\bar{x}-a}{b}$,

and the standard deviation is given by $\sigma_y = \dfrac{\sigma_x}{b}$.