Hypothesis and sample size calculation
The required sample size was calculated by using a two-sided McNemar test with 90 % power and 0.05 alpha, with the null hypothesis that the two marginal probabilities for each outcome in the 2 × 2 contingency table are the same (i. e. the performance of the POLAR system and the endoscopist are similar).
The clinical validation study was designed to find a 10 % difference in diagnostic accuracy of optical diagnosis between the POLAR system and the participating screening endoscopists. Based on previous research, we assumed a difference between the optical diagnosis by the POLAR system and the endoscopists in 20 % of 1–5 mm polyps (regardless of whether this optical diagnosis was correct or not)
