La table donne la limite inférieure de U, U étant la plus petite des deux valeurs Uab ou Uba ; ma et mb sont les effectifs des deux séries, ma étant le plus petit. Le symbole - veut dire que la différence n'est jamais significative (au seuil 5 %).
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Exemple : Pour ma = 5, mb - ma = 1, ( mb = 6), la différence-est significative, avec un risque < ou = 5 %, dès que U < ou = 3.
(*) D'après JACOBSON, J. E., Journ. of the Amer. Stat. Ass., 1963, 1086 (in : SCHWARTZ 1991, p.296).
NB : les mots suivis de "*" font partie du vocabulaire statistique, donc leur définition doit être connue. Faites-vous un glossaire.