alue from the studentized range distribution. The
    element at index ``(i, j)`` is the p-value for the comparison
    between groups ``i`` and ``j``.

Notes
-----
The string representation of this object displays the most recently
calculated confidence interval, and if none have been previously
calculated, it will evaluate ``confidence_interval()``.

References
----------
.. [1] NIST/SEMATECH e-Handbook of Statistical Methods, "7.4.7.1. Tukey's
       Method."
       https://www.itl.nist.gov/div898/handbook/prc/section4/prc471.htm,
       28 November 2020.
c