An article in the New England Journal of Medicine describes a randomized controlled trial that compared early versus late initiation of dialysis on the survival of adults with progressive chronic kidney disease. The experiment found no significant difference between early and late initiation of dialysis. According to the article, the study was designed to have power 80%, with a two-sided Type I error of 0.05, to detect a clinically important difference of approximately 10 percentage points in the absolute risk of death.
What fixed significance level was used in calculating the power?