Washington — Founded in 1920, the private National Bureau of Economic Research is one of the nation’s premier research organizations, routinely issuing reports on such complex and politically charged questions as the interplay between interest rates and exchange rates, monetary policy in developing countries, and the effects of Medicare rules on pharmaceutical prices.

Today it issued a report tackling the subject of student lending.

In the 55-page report, two economics professors — Lance J. Lochner of the University of Western Ontario and Alexander Monge-Naranjo of Northwestern University — employ hundreds of advanced mathematical equations, tables, and footnotes to calculate and analyze quantities such as “unrestricted allocations” and “exogenous borrowing constraints.”

Their conclusion: “We show that the rising empirical importance of familial wealth and income in determining college attendance is consistent with increasingly binding credit constraints in the face of rising tuition costs and returns to schooling.”

What’s all that mean? An official with the National Bureau of Economic Research, who asked that he not be identified by name, says the professors appear to saying, “College costs are increasing, students are having a tougher time borrowing money, and therefore poorer students are having a harder time attending.”

A spokeswoman for the bureau, which is financed through government and foundation grants, had no estimate of what the research cost. —Paul Basken