"The researchers used a metric called a median multiple, which compares the average home price to the median yearly income for an urban region"

Wouldn't it be better to compare medians? (Median home price to median yearly income). It seems to me that you want to be robust to outliers in home price (Danielle Steele's mansion) in the same way that you're already robust to outliers in income (Mark Zuckerberg's paycheck)