Pearson2xK-class: Pearson's chi-squared test for contingency tables
Description
When we test for homogeneity of rates in a k-armed trial with binary endpoints,
the test statistic is chi-squared distributed with \(k-1\) degrees of
freedom under the null. Under the alternative, the statistic is chi-squared
distributed with a non-centrality parameter \(\lambda\).
The function get_tau_Pearson2xk then computes \(\tau\), such that
\(\lambda\) is given as \(n \cdot \tau\), where \(n\) is the number of
subjects per group. In adoptr, \(\tau\) is used in the same way as \(\theta\)
in the case of the normally distributed test statistic.