This report and the grades earned by the four major networks are based on information provided by them. The report focuses on the primetime scripted programs from Fall of 2006 to Fall of 2007 and on the Reality programs on the air in the same time period. http://www.nhmc.org/wp-content/uploads/2017/07/NLMC-Diversity-Report-Card-Overview-10-07-final-3.pdf
The network grading explanation: http://www.nhmc.org/wp-content/uploads/2007/07/2007-Network-Report-Card-Explanation.pdf