The FHFA HPI covers far more transactions than the Commerce Department survey. The CQHPI covers sales of new homes and homes for sale, based on a sample of about 14,000 transactions annually, gathered through monthly surveys. The quarterly purchase-only HPI is based on more than eight million repeat transaction pairs over 43 years. This gives a more accurate reflection of current property values than the Commerce Department index. The HPI also can be updated efficiently using data collected by Fannie Mae and Freddie Mac in the normal course of their business activity.