Lillian and Others Who Know:
I do think that researching early readers is one of the most difficult groups to find authentic, specific and actual-factual stats on, in part because the books are specialized and most folks do not have the specific experience and are only able to generalize. A lot of coaching on these for new author/illustrators is actually done in-house using the current stable, so there is less material floating 'out there' to learn from. Doing early readers takes inside knowledge, and knowledge is power. If you have good research resources/links, could someone please suggest sources?