Using the described search approach, no studies in the topic area of marriage accumulated in the search results. A supplemental search approach was used for this topic area that relied on team members knowledge of the marriage literature and focused searches of studies from the Fragile Families data set, which is known to focus on family processes, including marriage and relationships, in the low-income U.S. population. A similar process was used to identify studies in the topic area of substance abuse.
Both qualitative and quantitative studies were included; however, dissertations were not included. And although a search of the unpublished literature preliminarily turned up several articles, most were excluded because of a lack of focus on low-income groups.