Individual distribution identification provides goodness-of-fit statistics and distribution parameters for several commonly used distributions. Many of these distributions are versatile and can model a variety of continuous data, including data with positive values, negative values, and 0.
However, the following distributions can only be used to model data with positive values:
- 2-parameter lognormal
- 1-parameter exponential
- 2-parameter Weibull
- 2-parameter gamma
- 2-parameter loglogistic
Therefore, if your data contain negative values or 0, Minitab does not report results for these specific distributions. In that case, use the results for the higher-parameter version of each distribution. For example, if your data contain negative values, Minitab does not report results for the 2-parameter lognormal distribution. Instead, use the results for the 3-parameter lognormal distribution.
For more information on the distributions used in individual distribution identification, go to Why is Weibull the default distribution for nonnormal capability analysis?.