An additional question on ownership of cooperative shares was added for 1999 and 1996 in order to ensure a more accurate count of owner-occupied cooperative units. For 1999, the two countries India and Mexico became separate response categories in the question on last place lived and place of birth. Previously, each was included as part of a grouping of neighboring countries, respectively. For 1999, a series of questions on immigration to the United States and year moved to New York City replaced a set of questions on the previous residence of the householder. As a result of the differences noted above, comparisons between surveys should be made with caution particularly when comparing data with surveys prior to 1991.
All demographic surveys suffer from undercoverage.
This undercoverage results from missed housing units and missed persons within sample households. For units that have existed since 1990, our coverage is about one percent lower than that of the 1990 Decennial Census. The weighting procedures used by the Census Bureau partially correct for the bias due to undercoverage. However, its final impact on estimates is unknown. Capped Data See Appendix F for an explanation of topcoding .