Q-Q plots

The Q-Q plots procedure produces probability plots for transformed values. Available test distributions include beta, chi-square, exponential, gamma, half-normal, Laplace, Logistic, Lognormal, normal, pareto, Student's t, Weibull, and uniform. Depending on the distribution selected, you can specify degrees of freedom and other parameters.

  • You obtain probability plots for transformed values. Transformation options include natural log, standardize values, difference, and seasonally difference.
  • You can specify the method for calculating expected distributions and for resolving "ties" (multiple observations with the same value).

Obtaining Q-Q plots

This feature requires Statistics Base Edition.

  1. From the menus choose:

    Analyze > Descriptive statistics > Q-Q plots

  2. Click Select variables under the Variables section, select one or more categorical or quantitative variables, and then click OK.
  3. Optionally, you can expand the Additional settings menu and select the following options:
    • Click Test distribution to select test and distribution parameters.
    • Click Options to select transformation options to obtain probability plots for transformed values and specify a method for calculating expected distributions.
  4. Click Run analysis.