The study looked at Dutch mortgage data from 1996 to 2015 to see why some loans weren't being paid back. They found that higher loan-to-value ratios and debt-to-income ratios made it more likely for loans to go bad. Mortgages with government guarantees were less likely to have problems. Also, loans with certain characteristics, like interest-only loans or underwater borrowers, were riskier. The study suggests that setting loan-to-value limits at 70%-80% for uninsured mortgages and 90% for insured ones could help prevent more loans from failing.