A comparison of homogeneity tests for regional frequency analysis

[1] The assessment of regional homogeneity is a critical point in regional frequency analysis. To this end, many homogeneity tests have been proposed, even though a general comparison among them is still lacking. Commonly used homogeneity tests, based on L moments ratios, are considered here in a comparison with two rank tests that do not rely on particular assumptions regarding the parent distribution. The performance of these tests is assessed in a series of Monte Carlo simulation experiments. In particular, the power and type I error of each test are determined for different scale and shape parameters of the regional parent distributions. The tests are also evaluated by varying the number of sites belonging to the region, the series length, the type of the parent distributions and the degree of heterogeneity. We find that L moments based tests are more powerful when the samples are slightly skewed, while the rank tests have better performances in case of high skewness. On the basis of these findings we propose a simple method to guide the choice of the homogeneity test to be used for the different possible cases.