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Power for detecting effect sizes of size 1 (green), 2 (blue) and Type I error (red) when estimating degrees of freedom with the containment method (solid) and the Kenward-Roger method (dashed). The standard deviation of treatment effect is 0.01 in (A), 0.5 in (B), and 1 in (C). Black horizontal line is at 0.05 – the significance level.
