Maican, Florin G.Sweeney, Richard J.2013-06-032013-06-032013-051403-2465http://hdl.handle.net/2077/32930JEL Classification: C15; C22; C32; C33; E31; F31.If the researcher tests each model in a battery at the a % significance level, the probability that at least one test rejects is generally larger than a %. For five unit-root models, this paper uses Monte Carlo simulation and the inclusion-exclusion principle to show for a %=5% for each test, the probability that at least one test rejects is 16.2% rather than the upper-bound of 25% from the Bonferroni inequality. It also gives estimated probabilities that any combination two, three, four or five models all reject.13 pagesengreal exchange ratesunit rootMonte Carlobreak modelsText