Table 2 Results of randomization tests comparing the observed differences (D₀) in mean attachment strength between mussels occurring in natural orthoquartzite and loess platforms (sites pooled) with the difference in mean attachment strength when sites are randomly assigned to either rock type (D _i ). D_{i (0.025)} and D_{i (0.975)} are the upper and lower confidence limits obtained for D _i after 10,000 randomizations. P values are the proportion of all the D _i s that are greater than or equal to D₀

From: Does rock type account for variation in mussel attachment strength? A test with Brachidontes rodriguezii in the southwestern Atlantic