The difference between having no books in the home and having 500 books in the home has an enormous impact on schooling: Evans, Kelley, Sikora and Treiman (2010) did a study of about 70,000 15 year olds in 27 countries, interviewed. Their major result: Controlling for parental education, fathers' occupation, and social class, young people in homes with 500 books stay in school three years longer than children in bookless homes.
The effect of books in the home was about the same as the effect of parental education: Controlling for all other factors, those from homes in which parents had a college education stayed in school three years longer than those from homes in which parents had three years of education.
The effect of books was twice as strong as the effect of fathers' occupation. Children from homes in which fathers were professionals stayed in school about a year and a half longer than children from homes in which the father was a laborer, all other factors equal.
The effect of books was stronger than the effect of GDP (gross domestic product); children in the country with the highest GDP (United States) stay in school two years longer than children in the country with a much lower GDP (China).
In other words: Access to books is as strong as or stronger than economic factors, once again suggesting that access to books can mitigate the effects of poverty .
Another important result was the finding that the effects of books in the home are more powerful for children whose parents have little or no schooling. The results of the study predict that children of parents with little or no schooling who have 25 books in the home will have two more years of education than a similar family with no books in the home. Also, 500 books in the home predicts an additional two years of education.
Here is another way of looking at this result: 40% of children of parents with little or no education in bookless homes finish grade 9. In book-filled homes (500 or more books), 88% do.
Evans, Kelley, Sikora, and Treiman (2010) Family scholarly culture and educational success: Books and schooling in 27 nations. Research in Social Stratification and Mobility
(above review written by S. Krashen)