Keith Curry Lance's Colorado studies are based on over 15 years of in-depth studies and reflect similar results in approximately 10-20 other states' informal studies. See a summary video here.
Dr. Stephen Krashen has studied language acquisition and reading in depth.
He authored The Power of Reading: Insights from the Research, a meta-analysis of the research on reading for several decades. Listen to a summary as he addresses the LAUSD School Board.
Summary:
Poverty affects reading. School libraries are the greatest tool to overcome this gap, and certified librarians impact learning, and adequately staffed school libraries are important. This means us!
Libraries affect reading.
Library staffing affects reading.
Qualified library staffing affects reading.
Adequate support staff affects reading.
Qualified support staff affects reading.
Quantity of library books affects reading.
Quantity of library books affects reading.
Administrative understanding of the librarians' role and support for the librarians affect reading and learning.
Free Voluntary Reading (Sustained Silent Reading, Drop Everything and Read, etc.): Allowing students time to read quietly without interruption, without accountability, purely for pleasure, something that they choose will improve reading.
Students do better on state tests in schools if they have full-time, certified school librarians with well-funded collections with a variety of resources, if they are able to visit the library often and check out materials often, and if they have access to technology that is connected to library materials.
When they are allowed to do this, school librarians impact test scores:
Other studies are summarized here and here.
More Collaboration = Higher Scores
Summary: Using data from the National Center for Education Statistics, fewer librarians resulted in lower reading scores or slower rises in reading scores, and these scores are not attributable to other factors. More certified school librarians mean higher reading scores.
"Principals don't understand what a librarian brings to the position that an aide or parent volunteer cannot....If libraries are kept open by volunteers, then they become littler more than warehouses. The negative impact on student achievement may not be immediately evident, but it will be substantial."
"If a school doesn't have a dedicated teacher-librarian, kids will read less and be less comfortable evalusting information....Kids will have gaps in what they know about technology and how to use it ethically and responsibly."
Lance, Keith C., and Linda Hofschire. "Something to Shout About: New Research Shows That More Librarians Means Higher Reading Scores."School Library Journal 09 (2011): n. pag. School Library Journal. Web. 17 Mar. 2015. <http://www.slj.com/2011/09/industry-news/something-to-shout-about-new-research-shows-that-more-librarians-means-higher-reading-scores>.