All statistics and graphs for Box-Cox Transformation

The plot shows estimated standard deviations for the standardized transformed values, Z_i. For more information, go to Methods and formulas.

The lower CL is the lower confidence limit for the 95% confidence interval for λ. The upper CL is the upper confidence limit for the interval. Both confidence limits are displayed on the plot as dotted vertical lines. The value for each limit is given in the table.

The dashed horizontal line that is labeled Limit shows the estimated standard deviations for the standardized transformed values, Z_i, that results from using the value of λ that is equal to the lower CL or the upper CL. All λ values that fall within the confidence interval result in standard deviations that fall below the limit line.

Minitab estimates the optimal value for λ. The optimal value is the value that minimizes the estimated standard deviation of the standardized transformed values, Z_i. For more information, go to Methods and formulas.

If an appropriate rounded value for λ falls within the confidence interval, then you can use the rounded value instead of the optimal value. The rounded λ values correspond to understandable transformations, such as the square root (λ = 0.5) or the natural log (λ = 0).