England: „SES gaps (Anm.: SES = Socioeconomic status) widens over the course of secondary school with students in the bottom SES quintile making -.21 SD (Anm.: SD = standard deviation) less than expected progress and those in top quintile making .20 SD more than expected progress.“
Univ.-Prof. Dr. Steve Strand, „Ethnicity, gender, social class and achievement gaps at age 16“ (2014), S. 18