Based on the information summarized in Exhibit 3.1, at first glance it appears that there is a great deal of similarity in how researchers have constructed their hardship indexes. The indexes define hardship in terms of direct measures of families' experiences and actual living conditions, and include a core set of basic needs and food insecurity indicators. The indexes also are unweighted and draw their data from the SIPP.
Despite these similarities, however, there is variation in the number and types of indicators researchers have used to create their material hardship indexes. For example, about half of the studies include indicators of housing quality in their hardship index and only four studies include a measure of whether a family lives in crowded housing. Furthermore, even in cases where all studies include the same basic indicator (i.e., food security, housing security, or basic utilities), researchers have used different questions and combinations of questions to construct these indicators.
Given this variability in how researchers have defined and measured material hardship in their indexes, it is difficult to identify either a preferred approach to developing hardship indexes or agreement on a "core" set of indicators or measures or material hardship. Moreover, the differences among hardship indexes also make it difficult to compare the results from these studies both for specific aspects of hardship such as food or housing, and for overall material hardship.
This lack of consistency in how researchers have created their indexes reflects the complexities associated with creating a composite measure of material hardship. While the frequent use of the SIPP as a data source for analyzing material hardship to some extent standardizes the types of indicators and measures included in hardship indexes, there is still much to be learned about how SIPP measures may be used and combined to identify material hardship among families with children. To further our understanding of the complexities faced when defining and measuring material hardship, Chapter 4 presents new descriptive analyses of the SIPP measures that have most frequently been used by researchers to construct material hardship indexes. These analyses provide a closer look at the SIPP and how its measures relate to other constructs, such as household income, where a household lives, and family structure, and each other.
(4) Mayer & Jencks (1989) found that their weighted scale correlates 0.98 with their unweighted scale of eight hardships. As a result, they only use the unweighted scale when reporting their results.
(5) USDA has developed a comprehensive 18-item scale and Short-form scale, with only 6 items, to describe food security. Eight of the studies examined here, with the exception of Danziger et al. (2000), use a more limited set of specific questions to construct their food-related hardship indicators, sometimes only using one or two questions to describe this condition. The USDA food security scale was developed after the 1991 and 1993 SIPP panels were fielded and the 1996 SIPP panel uses a different six-item food security scale, which contains modified versions of some of the USDA questions. The questions have been adapted from a 12-month reference period (as asked in the CPS) to a 4-month period, and the Economic Research Service has developed an algorithm that maps responses to the SIPP questions to the USDA's three-point scale (food secure, food insecure-without hunger, and food insecure-with hunger). (See Survey of Income and Program Participation 1996 Wave 8 Food Security Data File, Technical Documentation, and User Notes).
(6) The 1999 American Housing Survey (AHS) shows 2.5% of all US occupied housing units as crowded, with a 7% rate for households in poverty, and 13% for Hispanic households (Richardson, 2001).