Application and extension of a likelihood-ratio test for seasonality in epidemiological data

ABSTRACT We present a detailed exposition of the development and application of a likelihood-ratio test for seasonality. It is well known that likelihood-ratio tests have optimal power properties. We assess the test's performance by means of a simulation study. The test's application is illustrated with three examples that have different alternative hypotheses, thus extending the original presentation of the test. These examples are not artificial or contrived, but they come from actual, real applications. As far as we know, these are the only completely worked-out examples of this test's application that are available in the literature. Thus, our exposition can serve as a tutorial on the test's application. Our presentation is detailed so as to facilitate further extension and application of the test to other alternative hypotheses. We supply pertinent R computer code in an appendix. For those who teach maximum-likelihood estimation, our examples provide interesting, real-life cases that may be used in teaching.