Figure 2

Comparative composite z-score distributions for four cohorts of DEP and GEP Irish/UK and North American students in SC1 and SC2 examinations. The upper and lower margins of the box represent the 75th and 25th quartiles of the distribution (the interquartile range) and the thick horizontal line within the box defines the median value. The vertical lines above and below the box represent the range of the data up to 1.5 times the interquartile range above and below the 75th and 25th quartiles. Values that are more than 1.5 times greater or less than the 75th and 25th quartiles are defined as outliers and are shown as dots.