Emily Silberstein’s is Head of Asia at Entrepreneurial Finance Lab, which helps lenders use psychological tests to gauge credit risk. In the article linked above, she reports these non-obvious results about characteristics that are predictive of loan repayment:

1. Honest people are more likely to pay loans, but not if they are super-honest. Emily speculates that super-honest people may be slow to detect the dishonesty of others they deal with.
2. Optimism is positively correlated with loan repayment for young people, but negatively correlated with loan repayment for older people.
3. People who feel they have control over their own lives are more likely to repay loans. People who feel that outside forces control their lives are less likely to repay loans.
4. However, cultural difference in the way people answer the questions used to assess this should be taken into account.