Fig. 6
From: Equal opportunities for all? Analyzing within-country variation in school effectiveness
Mean number of books at home by age in months in the 13 samples. The x-axis depicts the age in months and the y-axis depicts the mean numbers of books at home. The books at home variable was assessed through student questionnaires and ranged between 1 = none or very few (0–10 books) to 5 = enough to fill three or more bookcases (more than 200 books). The black dots indicate lower grade students and the grey dots upper grade students