Specify a transformation for Between/Within Capability Analysis

Stat > Quality Tools > Capability Analysis > Between/Within > Box-Cox
Use the Box-Cox transformation to transform your data to fit a normal distribution.

You can only use the Box-Cox transformation with positive data.

Select the lambda (λ) value that Minitab uses to transform the data.
  • Use optimal λ: Use the optimal lambda, which should produce the best fitting transformation. Minitab rounds the optimal lambda to 0.5 or the nearest integer.

    To use an exact value instead of a rounded value for optimal λ, choose File > Options > Control Charts and Quality Tools > Other and deselect Use rounded values for Box-Cox transformations when possible.

  • λ = 0 (ln): Use the natural log of your data.
  • λ = 0.5 (square root): Use the square root of your data.
  • Other (enter a value between -5 and 5): Use a specified value for lambda. Other common transformations are square (λ = 2), inverse square root (λ = −0.5), and inverse (λ = −1). In most cases, you should not use a value outside the range of −2 and 2.