The study looked at Dutch mortgages from 1996 to 2015 to see why some people couldn't pay them back. They found that higher loan-to-value ratios and debt-to-income ratios made it more likely for people to not pay. Mortgages with government guarantees were less likely to have problems. Also, loans where people only paid interest or owed more than their home was worth were riskier. The study suggests that to prevent more people from not paying, the loan-to-value limit should be around 70%-80% for mortgages without insurance, and around 90% for insured ones.