„Norway is a wealthy and egalitarian country with a homogeneous educational system, yet achievement gaps between students at the 90th and 10th percentiles of parental income and between students with parents who have at least a master and at most a high school degree are large, increasing by grade level. Gaps are equivalent to approximately 2-2.5 years of schooling.“
Univ.-Prof. Dr. Astrid Marie Jorde Sandsør u. a., Achievement Gaps by Parental Income and Education Using Population-Level Data from Norway (2021), S. 2.