Relationship of OverallMark at medical school to Educational Attainment (zEducationalAttainment). Scattergrams are shown separately for a) General Certificate of Education (GCE) qualifications (A-levels/AS-levels/GCSEs), and b) Scottish Qualifications Authority (SQA) qualifications (Scottish Highers and Advanced Highers). The red line is a linear regression, and the green line is a lowess curve. The slope of the line for SQA qualifications (b = .423) is significantly larger than that for GCE qualifications (b = .349; interaction term, t = 25.95, 3,428 df, P <.001).
McManus et al. BMC Medicine 2013 11:244 doi:10.1186/1741-7015-11-244