Comparability
Changes in the universe impact comparability over time. In 2000, this question was asked of female sample adults ages 40 and older. Beginning in 2005, this question was asked of female sample adults ages 18 and older. Additionally, in 2000, this question was asked as part of a series of possible medications that the respondent might be taking (including hormone replacement therapy, Tamoxifen, of Raloxifen). Beginning in 2005, respondents were asked separately whether they were currently using birth control pills, birth control implants, or birth control shots. These changes reduce comparability between 2000 and later years.
This variable is comparable for 2005-forward.
