Exact power and sample-sire computations for the Cochran-Armitage trend test

The Cochran-Armitage test of trend is commonly used to determine if a dose- response relationship exists in a wide variety of biomedical settings inclu ding clinical trials, carcinogenicity studies, and toxicological risk asses sment. For small, sparse, or unbalanced data sets, one generally adopts the exact version of the Cochran-Armitage test of trend for which numerical al gorithms and software are readily available. No corresponding algorithms or software exist for the exact power and sample-size computations that are n eeded at design time, prior to gathering the data. This paper develops a ne twork algorithm for computing the exact power of the Cochran-Armitage test of trend and applies it to several examples, thereby demonstrating that the corresponding asymptotic power computations can be rather misleading.