Evaluating the agreement of two quantitative assays with repeated measurements

A common task in assay validation is to show the agreement between an assay under investigation and a reference assay. Hence, in the hypothesis setup, we should choose nonagreement as the null hypothesis so that when the null hypothesis is rejected at 5% level of significance, we have a 95% statistical assurance to claim the agreement between two assays. In this paper, we propose a statistical test with nonagreement as the null hypothesis. The calculation of sample size is also given. Some simulation results are provided for illustration.