(i) Carry out a two-sample t-test to compare the mean time between occurrences of safety violations for operator "A" to that for operator "B"; carry out a second two-sample t-test comparing the means for operator "A" to that for operator "C". Are these valid tests?
(ii) Carry out a MWW test to compare the safety performance of operator "A" to that for operator "B" and a second MWW test to compare operator "A" to operator "C". Are these valid tests? Interpret your results and compare them to the results in (i). What conclusions can you reach about these operators and how safety conscious "B" and "C" are in comparison to "A"?