“…Values of relative difficulty index (RDI) items should range between 0.40 and 0.60, and those of measures of sampling adequacy (MSA)-a useful index for debugging inappropriate items before a factor analysis solution-should all be above 0.50, suggesting that each item measures the same domain as the remaining items in the pool, and so should not be removed [48]. Item 22 would thus be the only item occupying the first quartile, while items 15, 2, 16, 14, 1, 13, 9, 8, 20, 17, 5, 12, 21, and 19 would occupy the second quartile and items 23,7,11,3,6,24,25,10,4, and 18 would be part of the third quartile. Overall, the lower the level in the quartile, the lower the level of difficulty of the item, as indicated in Table 4.…”