Each month Fannie Mae conducts a survey of approx. 1,000 Americans via telephone interview. Fannie Mae's National Housing Survey is the most detailed consumer survey conducted right now. 
The goal of this survey is to assess their individual attitudes toward: 

Owning or renting their home
Home rental price changes 
Homeownership distress
The current economy 
Household finances
Overall consumer confidence
  The homeowners and renters surveyed are asked more than 100 questions. Their answers are used to help track shifts in their attitudes toward homeownership. Their answers will help industry partners and market participants target the collective efforts to stabilize the housing market. 
  The answers that Fannie Mae collects from the survey are then used to help create the Home Purchase Sentiment Index (HPSI). The HPSI takes all of the information gathered and creates a single number to be used. The number then reflects the current c; ...