The y-axis is actual_score - self_assessed_score, right? So we are interested in whether the average of this y-axis value differs between high scoring and low

The y-axis is actual_score - self_assessed_score, right? So we are interested in whether the average of this y-axis value differs between high scoring and low scoring groups. The study that shows there is no D-K effect [1] linked by the OP article shows there isn't a difference in the average value (y-axis) between groups. In fact the mean value was 0 for all quartiles. So we can conclude that we have found no systematatic over/under reporting of actual vs percieved skill. People in the lowest quartile do not appear to position themselves higher than they should. Or at least, we can't reject the null hypothesis 1. See figure 2 on page 15, note that zero means agreement between self-assessed and actual: https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=1215&context=numeracy https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=1...