Box Cox Transformation. Minitab will select the best mathematical function for this data transformation. This assumption allows us to construct confidence intervals and conduct hypothesis tests.
If your data isn t normal applying a box cox means that you are able to run a broader number of tests. Y λ y λ 1 λ if y 0. A box cox transformation is a transformation of a non normal dependent variables into a normal shape.
Box cox transformation was first developed by two british statisticians namely george box and sir david cox.
Y λ y λ 1 λ if y 0. If one of the sample values is not positive then we add 1 a to all the sample values where a is the smallest sample value. The statisticians george box and david cox developed a procedure to identify an appropriate exponent lambda l to use to transform data into a normal shape the lambda value indicates the power to which all data should be raised. Y λ y λ 1 λ if y 0.
