Also - were the people interviewed all in the USA (as a disproportionate number of psychology studies are)? Because 'income' doesn't mean much without looking at what you get for free from the government - e.g. in a lot of European countries, people don't have to worry about paying for healthcare, higher education or getting paid for sick leave or maternity.. so they wouldn't necessarily need as much of an income to feel safe and relaxed.

Thank you for this! I did always feel that this study was suspect.