The list of addresses the Census Bureau used to select the Puerto Rico Community Survey (PRCS) sample underwent substantial changes in 2010, and to a lesser extent, in 2011. These changes are the result of 2010 Census address canvassing and enumeration activities. Due to these changes and the lack of independent housing unit estimates to use as controls in the weighting process, the PRCS estimates of total housing units and households, as well as vacant housing units, changed significantly between 2009 and 2010 and also between 2010 and 2011.

In addition, as a result of the weighting methodology procedure to generate consistent estimates of householders, households and occupied housing units, users may see impacts in other PRCS characteristics such as relationship and marital status, and average household size due to the change in occupied housing units.

For these reasons, the Census Bureau recommends using caution when comparing PRCS estimates across these years. The Census Bureau is taking the following steps to address this issue for the future: 1) working with the Commonwealth of Puerto Rico to develop independent housing unit estimates that can be used as housing unit controls; and 2) revising the weighting methodology to address unexpected changes in the housing unit inventory.