FAQ/ChiMono - CBU statistics Wiki

In particular for N sequences of length k the number expected by chance is $$\frac{N}{k!}$$. We end up with two sets of observed and expected frequencies representing the number of individuals showing either strictly increasing or strictly decreasing trends over time (or some other category) and those who do not. These are then compared using Pearson's chi-square with a significant p-value indicating either greater or fewer occurrences of strictly increasing or strictly decreasing individuals than would be expected by chance.