Studies of Welfare Populations: Data Collection and Research Issues. Administrative Data, Matched Data, and Data Linkage

06/01/2002

Before defining privacy and confidentiality, it is useful to define what we mean by administrative data, matched data, and data sharing. Our primary concern is with administrative data for operating welfare programs--"all the information collected in the course of operating government programs that involve the poor and those at risk of needing public assistance" (Hotz et al., 1998:81). Although not all such information is computerized, more and more of it is, and our interest is with computerized data sets that typically consist of individual-level records with data elements recorded on them.

Records can be thought of as "forms" or "file folders" for each person, assistance unit, or action. For example, each record in Medicaid and UI benefit files is typically about one individual because eligibility and benefit provisions typically are decided at the individual level. Each record in TANF and Food Stamp Program files usually deals with an assistance unit or case that includes a number of individuals. Medicaid utilization and child protective services records typically deal with encounters in which the unit is a medical procedure, a doctor's visit, or the report of child abuse.

Records have information organized into data elements or fields. For individuals, the fields might be the name of the person, his or her programmatic status, income last month, age, sex, and amount of grant. For encounters, the information might be the diagnosis of an illness, the type and extent of child abuse, and the steps taken to solve the problem, which might include medical procedures or legal actions.

It is important to distinguish between statistical and administrative data. Statistical data are information collected or used for statistical purposes only. Data gathered by agencies such as the U.S. Census Bureau, Bureau of Labor Statistics, Bureau of Justice Statistics, and the National Center for Health Statistics is statistical data. Administrative data are information gathered in the course of screening and serving eligible individuals and groups. The data gathered by, for example, state and local welfare departments are an example of administrative data. Administrative data can be used for statistical purposes when they are employed to describe or infer patterns, trends, and relationships for groups of respondents and not for directing or managing the delivery of services.

Administrative data, however, are used primarily for the day-to-day operation of a program, and they typically only include information necessary for current transactions. Consequently, they often lack historical information such as past program participation and facts about individuals, such as educational achievement that would be useful for statistical analysis. In the past, when welfare programs were concerned primarily with current eligibility determination, historical data were often purged and data from other programs were not linked to welfare records. Researchers who used these data to study welfare found that they had to link records at the individual or case level over time to develop histories of welfare receipt for people. In addition, to make these data even more useful, they found it was worthwhile to perform data matches with information from other programs such as UI wage data; vital statistics on births, deaths, and marriages: and program participation in Medicaid, the Food Stamp Program, and other public programs. Once this matching was completed, researchers expunged individual identities, and they analyzed the data to produce information about overall trends and tendencies. Matched files are powerful research tools because they allow researchers to determine how participation in welfare varies with the characteristics of recipients and over time. They also provide information on outcomes such as child maltreatment, employment, and health.

Matched administrative data are becoming more and more widely used in the evaluation and management of social programs. In February 1999, UC Berkeley's Data Archive and Technical Assistance completed a report to the Northwestern/University of Chicago Joint Center for Poverty Research that provided an inventory of social service program administrative databases in 26 states (1) and an analysis of the efforts in these states to use administrative data for monitoring, evaluation, and research. Unlike other studies that have dealt with data sharing in general, this study was concerned primarily with the use of administrative data for research and policy analysis.

The UC study found that the use of administrative data for policy research was substantial and growing around the country. More than 100 administrative data-linking projects were identified in the study sample. Linkages were most common within public assistance programs (AFDC/TANF, Food Stamp Program, and Medicaid), but a majority of states also had projects linking public assistance data to Job Opportunities and Basic Skills, UI earnings, or child support data.

Approximately a third of the states had projects linking public assistance data to child care, foster care, or child protective services. Four-fifths of the states used outside researchers to conduct these studies, and about half of all the projects identified were performed outside of state agencies. The vast majority of projects were one time, but there is a small, and growing, trend toward ongoing efforts that link a number of programs.

Figure 8-1 indicates the likelihood of finding projects that linked data across eight programs. Programs that are closer on this diagram are more likely to have been linked. Arrows with percentages of linkage efforts are included between every pair of programs for which 35 percent or more of the states had linkage projects. Percentages inside the circles indicate the percentage of states with projects linking data within the program over time. AFDC/TANF, Food Stamp Program, and Medicaid eligibility are combined at the center of this diagram because they were the major focus of the study and because they are often combined into one system. The diagram clearly shows that there are many linkage projects across data sets from many different programs, frequently involving sensitive information.

Figure 8-1:
Percent of states with projects linking data from social service programs

Figure 8-1 Percent odf states with projects linking data from social service programs

Source: U.C. Data Archive and Technical Assistance(1999)

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