Transform nonnormal data

You can transform your data using many functions such as square root, logarithm, power, reciprocal or arcsine.

To apply these transformations directly to your data in the worksheet, use the Minitab Calculator.
To perform a Box-Cox transformation, choose Stat > Control Charts > Box-Cox Transformation.
Minitab determines an optimal power transformation. The Box-Cox transformation is easy to understand, but is limited and often does not determine a suitable transformation. It is also only available for data that are positive.
To perform a Johnson transformation, choose Stat > Quality Tools > Johnson Transformation.
If the Box-Cox algorithm does not determine a suitable transformation, then try the Johnson transformation. The Johnson transformation function is more complicated, but is very powerful for determining an appropriate transformation.