Fig. 2.
Joint distribution histograms. (a) JDH of a pair of pre-treatment coffee-break exams. The green line represents the linear regression of the JDH, which is the diagonal line in this case. The magenta lines represent the 97.5th and 2.5th percentile, respectively; i.e., the area between the magenta lines is 95% confidence interval for the null distribution. (b) JDH of a pair of pre- and post-treatment exams. The green line represents the diagonal line and the magenta lines represent the 97.5th and 2.5th percentile lines of the null distribution, respectively. Note that the magenta lines in (a) and (b) are of different intercepts. The magenta lines in (a) are the 97.5th and 2.5th percentile for this specific coffee-break exam pair. The magenta lines in (b) are the average 97.5th and 2.5th percentile for the 5 pairs of coffee-break exams in the training data sets.