Variance component analyses show that, regardless of scoring method, biological variation among different patients was the largest component of the total variation, indicating that the Ki67 score is reflecting inherent properties of the tumor and that the effect on the score introduced by the immunohistochemistry assay technical variation (sectioning, staining, and scoring) is relatively small (Figure 2, Supplementary Table 5). The gene discussed is MKI67; the disease is neoplasm.