A local training firm has developed an innovative programme to improve the performance of students on the courses it offers. To assess whether the new programme improves student performance the firm have collected two random samples from the population of students sitting an accountancy examination, where sample 1 students have studied via the traditional method and sample 2 students via the new programme. The firm has analysed previous data and the outcome of the results provides evidence that the distribution is not normally distributed, but is skewed to the left. This information results in concern at the suitability of using a two sample independent t-test to undertake the analysis and, instead, they decide to use a suitable distribution-free test. In this case the appropriate test is the Mann–Whitney U test.