The study looked at how different lenders handle mortgage applications from minority and low-income applicants. They used data from over 8,600 lenders in the US in 1990 to see if there were differences in how these lenders treated applications from different groups. The researchers found that most of the variation in loan approvals for minority and low-income households was due to differences in the number of applications received by lenders, rather than how the lenders decided on those applications. This suggests that the disparities in lending to these groups are more about the number of applications lenders get, rather than discrimination in the loan approval process.