Counting by weighing and its effect on comparing population proportions

Counting by weighing is a rapid procedure for obtaining NN items (e.g., seeds) based on weight rather than exact counting. We show how to modify the test statistic used for comparing mm population proportions (e.g., seed germination rates) when independent samples are taken using this approximate counting procedure. The modified test will have approximate size αα as advertised under the null hypothesis that there is no difference among the mm proportions. A simulation study is conducted to determine the small to moderate sample size Type I error rates of the classical and modified tests.