CLASSROOM NOTES Sensitivity of the ?<sup>2</sup> Goodness-of-Fit Test to the Choice of Classes.

The ?<sup>2</sup> goodness-of-fit test is often one of the first tests of hypotheses encountered by students. When some of the expected frequencies are small, classes need to be combined. A real-life example is given that illustrates a surprising sensitivity of the results of the test to the way in which such combinations are chosen.