A graphical presentation of the step-wise procedure for determination of Ki67 status. The black jagged line corresponds to the null hypothesis of probability 0.20 of a positive cell, the cut-off. The dark region covers the counts for which the null hypothesis cannot be rejected by a two-sided binomial test at the 1.0% significance level. If the estimate falls in this region, another 10 cells are counted and a new test is performed. If 400 cells have been counted without reaching the upper or lower rejection regions (light regions), the Ki67 status of the sample is considered equivocal. If the upper or lower rejection region is reached for a sample, the counting is stopped, and the Ki67-status determined.