Randomizes a binary matrix speciesData by reshuffling elements within each column equiprobably.
This algorithm assumes species are equiprobable, but preserves differences among sites (= column sums).
This algorithm preserves differences in species richness among sites (= colsums), but assumes that all species are equiprobable. This assumption is usually unrealistic, and sim3 has a high frequency of Type I errors with random matrices, so it is not recommended for co-occurrence analysis.
Gotelli, N.J. 2000. Null model analysis of species co-occurrence patterns. Ecology 81: 2606-2621.
randomMatrix <- sim3(speciesData=matrix(rbinom(40,1,0.5),nrow=8))