Here are their conclusions:
The library emerged as a consistent predictor of reading scores for children in the United States taking a national reading test. Library quality was a significant and strong predictor of fourth grade (NAEP) reading scores, and was a predictor of the difference between fourth and eighth grade NAEP reading scores. This second result suggests that libraries play an important role in stimulating reading improvement in students between grades four and eight.
In a second report, Krashen, Lee and McQuillan reported that the library was also a strong predictor of reading scores for ten year olds in 40 different countries (data taken from the PIRLS study). These results are remarkable for several reasons:
- The measures used were crude: library holdings, and even general circulation, in the case of public libraries.
- The results held even when other powerful factors, such as poverty, were taken into consideration.
- The results held both for students in the US, and for students in 40 different countries.