The median home price in the US in 1970 was approximately $23,400, less than 2.5 times the median family income at the time of about $9,870. By last year, the median home price was more than $400,000, about 5 times the median family income of about $80,000. No surprise that people are warning about a housing affordability crisis. To what extent is that driven by the increasing cost of building homes? Chicago Booth's Chad Syverson talks about his research on the weak link between building costs and home prices. What's really behind the price increases in residential real estate?