A RESTRICTED TEST OF CIRCADIAN-RHYTHM

In medical applications there is interest in whether deaths or other e vents occur randomly throughout the day, as opposed to in a definite c ircadian pattern. At times, knowledge of the circadian phenomenon will suggest that a single cluster of events should occur during a specifi c period during the day, such as mid-morning. We propose a test that i ncorporates such knowledge. The test can be viewed as the likelihood r atio test for a restricted alternative for data from the von Mises (i. e., circular normal) distribution. The test's power is compared to a c ommonly used test of randomness that ignores when a peak is likely to occur. Methods for dealing with interval censored data are discussed, and an example is given. A Bayesian alternative is also explored.