Variation in expression of 13 candidate reference genes analysed by Equivalence test between tumour groups. Differences of the means (♦) and matching symmetrical confidence intervals (-) are shown for the log2-transformed relative gene expression. Y-axis represents the fold change in expression among subgroups. The deviation area [-l; l] for a fold change ≤2 lies within the dashed lines; the deviation area [-2; 2] for a fold change ≤3 lies within the solid lines. The gene is considered to be equivalently expressed, if the symmetrical confidence interval is a part of the deviation area and contains 0 in it. The variation in expression of the 13 reference genes was compared between benign vs. borderline and malignant tumours (A), benign and borderline vs. malignant tumours (B), benign vs. malignant tumours (C), mucinous vs. serous benign and borderline tumours (D), and serous vs. endometrioid malignant tumours (E).