What is “integration”?
Integration is the process of making data from different censuses or samples comparable. For example, most surveys ask about marital status; however, they differ both in their classification schemes (one survey might recognize only a general category of “married,” while another might distinguish between married, spouse present and married, spouse absent) and in the numeric codes assigned to each category (“divorced” might be coded as a “4” in one sample and as a “2” in another). To create an integrated variable for marital status we recode the marital status variable from each census into a unified coding scheme that we design.