The United States is considered the land of abundant food and most Americans are food secure, meaning access at all times to enough food for an active, healthy life. A proportion of the population experiences food insecurity at some time in a given year, however, because of food deprivation and lack of access to food due to economic resource constraints. Still, food insecurity in the United States is not of the same intensity as in some developing countries. The U.S. Department of Agriculture (USDA) estimated that in 2004 11.9 percent of U.S. households were food insecure at some time during the year. That means they did not have access at all times to enough food or were uncertain of having or were unable to acquire enough food for all household members because of insufficient economic or other resources. Of these, 3.9 percent of the households were estimated by USDA as “food insecure with hunger,” that is, food insecurity in the household reached levels of severity great enough that one or more household members were hungry at least some time during the year because they could not afford enough food (Nord, Andrews, and Carlson, 2005b, pp. 4–5). Such prevalence of food insecurity has economic and public health consequences for both the individuals and their communities as a result of reduced cognitive development and learning capacity in children, as well as lower intakes of food energy and key food nutrients and other similar conditions.
The statistics on food insecurity and hunger in U.S. households, published annually by USDA, are based on a survey measure developed by the U.S. Food Security Measurement Project, an ongoing collaboration among federal agencies, academic researchers, and private organizations. The mea-
sure was developed over the course of several years in response to the National Nutrition Monitoring and Related Research Act of 1990. It is a direct experiential measure based on self-reported behaviors, experiences, and conditions in response to questions in a survey. (A brief history of the development of the measure is provided in Chapter 2.)
Each year since 1995, USDA has developed annual estimates of the prevalence of food insecurity for U.S. households. These estimates are developed using data collected annually in the Food Security Supplement (FSS) to the Current Population Survey (CPS). On the basis of the number of food-insecure conditions that are reported by households (i.e., the number of questions the respondent affirms), USDA classifies households into one of three categories for purposes of monitoring and statistical analysis of the food security of the population: food secure, food insecure without hunger, and food insecure with hunger. Furthermore, the questions specify that the behavior or condition must be due to a lack of economic or other resources to obtain food, so the scale is not affected by hunger due to voluntary dieting or fasting or being too busy to eat or other similar reasons, or involuntary hunger due to reasons other than resource constraints. USDA uses statistical methods based on a single-parameter logistic item response theory model (the Rasch model) to assess individual questions and to assess the assumptions that justify using the raw number of items affirmed as an ordinal measure of food insecurity. (This method and the issues surrounding its use for this purpose are described in detail in Chapter 5.)
The USDA estimates, published in a series of annual reports since 1995, are widely used by government agencies, the media, and advocacy groups to report the extent of food insecurity and hunger in the United States, to monitor progress toward national objectives, to evaluate the impact of particular public policies and programs, as a standard by which the performance of USDA programs is measured, and as a basis for a diverse body of research on questions related to food assistance programs. Government agencies have also adopted the estimates as targets for performance assessment. The U.S. Department of Health and Human Services (DHHS) uses the food security measure to assess the performance of its Healthy People 2010 initiative. The Food and Nutrition Service of USDA is using the measure as a target for its strategic plan to fulfill requirements of the Government Performance and Results Act of 1993.1
Despite the extensive use of the measure over the years, some major questions continue to be raised related to the concepts, methods, and questionnaire items used by USDA for measuring food insecurity and hunger in the annual surveys.
While the USDA annual reports define the concepts of food insecurity and the three categories of food insecurity that are estimated and reported (i.e., food secure, food insecure without hunger, and food insecure with hunger), providing detail about how they are measured, the terms “food security” and “food insecurity” are relatively new to both policy makers and the public, and they are sometimes confusing. While the term “hunger” is not new, measurement of hunger and how hunger fits conceptually into food insecurity is not completely clear. As currently construed in USDA’s food insecurity measure, hunger could be considered a severe level of food insecurity. This use of the term “hunger” has been questioned by some who believe that hunger is conceptually distinct from food insecurity. Because the label “hunger” is a politically potent concept, the methods used to classify households as food insecure with hunger and the use of these estimates are particularly important.
Methodological and technical issues about the measure of food insecurity generally concern the appropriateness of the statistical model used in developing the food insecurity scale and the clarity and design of the CPS survey questions. Also of concern is the relatively long reference period, mixing questions focused on households with those on individuals, and using the same module to assess food insecurity among subgroups, such as households with and without children and the elderly population.
Questions about the appropriate uses of the estimates of food insecurity have also been raised. The media, advocacy groups, and others often interpret the prevalence estimates in language inconsistent with USDA usage. The primary use of the Food Security Supplement is to estimate the prevalence of food security and its severity levels. USDA has explicitly stated (Nord, Andrews, and Carlson, 2005a, p. 10) that:
technically the Food Security Supplement data do not support estimates of the number of people that experience hunger. USDA’s food security reports, based on the FSS, do not provide, nor claim to provide, statistics on the prevalence of hunger among individuals. The survey, and USDA’s reports based on it, provide upper and lower bound estimates of the number of adults and number of children who were hungry at times during the year. They also provide information that sheds light on the prevalence of hunger—by describing the experiential-behavioral context in which hunger occurs. (In early years of the Food Security Measurement Project, USDA analysts sometimes used wording such as “the prevalence of hunger” as shorthand for ‘the prevalence of food insecurity with hunger’ in official reports and research articles. In more recent years disciplined attention has
been given to avoid such statements because of a growing awareness of the conceptual and interpretive problems they can cause.)
This understanding is consistent with the Life Sciences Research Office conceptual definitions (which grew out of considerable public discussion of a wide range of definitional/conceptual alternatives), in the sense that hunger for an individual is a potential, although not necessary, consequence of food insecurity. Yet the media and advocacy groups often interpret the prevalence estimates in language inconsistent with USDA usage.
OBJECTIVES OF THE MEASURE
The measurement and monitoring activities related to the development of the measurement of food insecurity have a number of policy-related objectives:
Create a measure with generally agreed-on concepts, definitions, and measurement methodologies that estimates the frequency and severity of problems regarding access to food in a way that is standard and consistent over time and across subgroups of the population at national and state levels.
Provide objective, standardized information on the extent and severity of food insecurity and the characteristics of affected persons, so that allocation of public resources and development of public policies and programs can be based on informed public debate. The mission statement of the Food and Nutrition Service (FNS), which administers USDA’s food assistance programs, includes the goal of increasing food security: “FNS increases food security and reduces hunger in partnership with cooperating organizations by providing children and low-income people access to food, a healthful diet, and nutrition education in a manner that supports American agriculture and inspires public confidence.”
Provide data on household food security that can be used along with other survey information collected in surveys to assess the need for and effectiveness of public programs, especially food assistance programs; the causes of food insecurity at various levels of severity; and the effects of food insecurity on nutrition, health, children’s development, and other aspects of well-being.
Provide measures of food security that can be used consistently across the National Nutrition Monitoring and Related Research Program and in state, local, and special population surveys that can be compared meaningfully with national food security statistics.
THE PANEL’S STUDY
As indicated above, the USDA’s food security measures were designed a decade ago in partnership with DHHS. USDA decided that a thorough review at this 10-year mark is warranted, especially in light of persistent conceptual and methodological concerns about the concepts and their measurement. USDA’s Economic Research Service, through its Food Assistance and Nutrition Research Program, has expressed the need for a review of the conceptualization and methods used in measuring food insecurity, as well as the validity and utility of the measure for informing public policy. Promotion of food security is part of the mission of USDA’s Food and Nutrition Service, and certain food security measures constitute performance goals for that agency as required by the Government Performance and Results Act.
USDA requested the Committee on National Statistics of the National Academies to convene a panel of experts to provide an independent review of the current conceptualization and methods of measuring food insecurity and hunger in the U.S. population. The contract charge to the panel specifies that the 2-year study will be conducted in two phases. During Phase 1 of the study a workshop was to be held to address the key issues laid out for the study and a short report prepared based on workshop discussions and preliminary deliberations of the panel. The specific tasks to be addressed in Phase 1 include:
the appropriateness of a household survey as a vehicle for monitoring on a regular basis the prevalence of food insecurity among the general population and within broad population subgroups, including measuring frequency and duration;
the appropriateness of identifying hunger as a severe range of food insecurity in such a survey-based measurement method;
the appropriateness, in principle and in application, of item response theory and the Rasch model as a statistical basis for measuring food insecurity;
the appropriateness of the threshold scores that demarcate food insecurity categories—particularly the categories “food insecure with hunger” and “food insecure with hunger among children”—and the labeling and interpretation of each category;
the applicability of the current measure of the prevalence of food insecurity with hunger for assessing the effectiveness of USDA’s food assistance programs, in connection with the performance goals
pursuant to the Government Performance and Results Act (Public Law 103-62) for the Food and Nutrition Service; and
future directions to consider for strengthening measures of hunger prevalence for monitoring, evaluation, and related research purposes.
In Phase 2 of the study the panel was to consider in more depth the issues identified in Phase 1 relating to the concepts and methods used to measure food security and make recommendations as appropriate. In addition, the panel was asked to address and make recommendations on:
the content of the 18 items and the set of food security scales based on them currently used by USDA to measure food insecurity;
how best to incorporate and represent information about food security of both adults and children at the household level;
how best to incorporate information on frequency and duration of food insecurity in prevalence measures;
needs and priorities for developing separate, tailored food security scales for population subgroups, for example, households versus individuals, all individuals versus children, and the general population versus homeless persons; and
future directions to consider for strengthening measures of food insecurity prevalence for monitoring, evaluation, and related research purposes throughout the national nutrition monitoring system.
To address this two-phase request, the Committee on National Statistics appointed a panel of 10 members representing a range of expertise related to the scope of the study.
During the first phase of the study, the panel reviewed articles and papers prepared or sponsored by USDA to assess the methodological concerns about the food security measures and other published and unpublished papers.
The panel met on two occasions to deliberate on the issues listed above. The first meeting was held in March 2004. In the public part of the meeting, USDA staff and other experts in the field briefed the panel on the history of the conceptual and technical development of the measure and on the uses of the food security measure. Critics of the current measurement methodology presented their views, and USDA staff and other meeting attendees were given the opportunity to respond.
The panel held a large workshop to obtain input from a wide range of researchers and other interested members of the public. The Workshop on
the Measurement of Food Insecurity and Hunger was held on July 15, 2004.
Four background papers were prepared by experts and presented at the workshop (the full text of the papers is available at http//www.nationalacademies.org/cnstat):
Conceptualization and Instrumentation of Food Security by J.P. Habicht, G. Pelto, E.A. Frongillo, and D. Rose.
The Uses and Purposes of the USDA Food Security and Hunger Measure by P. Wilde.
Item-Response Models and Their Use in Measuring Food Security and Hunger by M.S. Johnson.
Alternative Construction of a Food Security and Hunger Measure from 1995 Current Population Survey Food Security Supplement Data by K. Alaimo and A. Froelich.
Discussants were asked to give their reactions to these papers, and open discussion sessions were set aside for general comments from participants. A roundtable discussion on the questionnaire design and cognitive aspects of the survey module was also held during the workshop.
In order to provide timely guidance to USDA, the panel issued an interim Phase 1 report, Measuring Food Insecurity and Hunger: Phase 1 Report. That report presented the panel’s preliminary assessment of the food security concepts and definitions, the appropriateness of identifying hunger as a severe range of food insecurity in such a survey-based measurement method, questions for measuring these concepts, and the appropriateness of a household survey for regularly monitoring food security in the U.S. population. It provided interim guidance for the continued production of the food security estimates. This assessment was based primarily on the review of the literature, public comments at the panel meetings, workshop presentations and discussions, and expert judgments of the panel.
For its Phase 2 research, the panel commissioned four additional background papers from experts in the areas of hunger, methods, cognitive aspects in questionnaire development, and comparison of selected surveys to provide expert and detailed analysis of some of the key issues beyond the time and resources of its members. These papers and their respective authors are listed below.
Methodological Issues in Measuring Food Insecurity and Hunger by M.S. Johnson.
Cognitive Aspects of the Questions Used to Measure Food Insecurity and Hunger by J. Dykema and N.C. Schaeffer.
A Comparison of Surveys for Food Insecurity and Hunger Measurement by S.J. Haider.
The Concept and Definition of Hunger and Its Relationship to Food Insecurity by D.H. Holben.
The full text of these papers is available at <http://www.nationalacdemies.org/cnstat>.
Scope and Limitations of the Study
The study is complex, covering wide-ranging issues from concepts and definitions, to survey design and implementation, to statistical methods and models, to application for assessing program performance. At the same time, its scope is limited to reviewing USDA’s measure of food insecurity as used in the annual survey. Many other issues relevant to the subject of food insecurity, such as the determinants and consequences of hunger, the relationship of obesity and food insecurity and hunger, the relationship between food insecurity and dietary intake, nutrient availability and health status, socially acceptable sources of food, and food safety, are important. These issues, however, are not intrinsically indicators of economic deprivation. Although the panel recognizes their importance, their measurement is beyond the scope of this study. Moreover, a full consideration of these issues should be the subject of separate studies.
As with most national household population surveys, the CPS excludes homeless people who are not in shelters. However, the question of including or excluding homeless people from the Food Security Supplement to the CPS is not as straightforward as for other household surveys. Omitting the homeless is likely to result in an undercount of the number of more severely food-insecure persons. The panel recognizes the likelihood of relatively high rates of food insecurity among homeless people, and the resulting negative bias resulting from their exclusion. At the same time, it has serious questions about the operational and methodological issues. Over the years, techniques have been developed to locate, sample, and obtain data about segments of this population. The Census Bureau has done a lot of experimentation in this area. Yet locating and screening respondents for eligibility require special efforts involving careful and long-term planning, substantial staff resources, considerable time, and high levels of funding. Much research and testing are required to develop the necessary protocols and procedures for conducting the Food Security Supplement in a separate survey among homeless people. Until better methods to survey the homeless are developed, continuing to limit the target population to the household population seems appropriate.
ORGANIZATION OF THE REPORT
The panel used three criteria to guide the content of the report and its recommendations. First, the subject area examined must be relevant to and within the scope and purview of the panel’s charge. Second, the evidence and analysis must be sufficient to support and justify its conclusions and recommendations. Third, recommendations should be attainable at reasonable cost.
The report focuses primarily on the Phase 2 charge and is organized in a manner responsive to the panel’s charge. Following this Introduction, Chapter 2 summarizes the history of the development of the concepts of household food insecurity and hunger and their operational definitions, the measurement and monitoring of food insecurity in the context of the United States using the Food Security Supplement to the Current Population Survey, and the uses of the food insecurity questions in other surveys nationally and internationally. Chapter 3 discusses the conceptual issues associated with the terms food insecurity and hunger and the operational definitions used to measure household food insecurity and hunger and the usage of labels for categories of food insecurity.
Chapters 4–7 examine a range of issues and needed changes leading toward improved measures of the prevalence of food insecurity and hunger. Chapter 4 reviews the current measurement of food insecurity and the validity and reliability of the questions used to measure food insecurity and hunger, identifying selected questions in the Household Food Security Survey Module that need improvements. Chapter 5 reviews the history and structure of latent variable models and describes the different ways of estimating latent variable models. The chapter then examines the method currently used by USDA to measure food insecurity and its prevalence and the various issues involved with the method used, suggesting better ways to match the item response theory models with the nature of the data collected in the food insecurity surveys. Chapter 6 reviews the key features of selected national sample surveys in terms of their capacity to include the Food Security Supplement, compares the relative advantages and disadvantages of the surveys, and provides recommendations for USDA’s future consideration. Chapter 7 examines the use of the estimate of the prevalence of food insecurity for assessing the performance of USDA’s food assistance programs in accordance with the Government Performance and Results Act of 1993.
Finally, Chapter 8 highlights the panel’s key conclusions. It emphasizes that the panel, in providing the critique and recommended actions for the future, recognizes the continuing research and concerted efforts to develop a standardized direct measure of food insecurity that can be used for monitoring purposes and related research that have been carried out by USDA and its collaborating agencies.
The panel hopes that the report and its recommendations will contribute to the development of a revised, efficient, and cost-effective system for monitoring the prevalence of food insecurity in the United States, as well as provide the basis for research to answer the important questions about the broader health and socioeconomic and psychological consequences of food insecurity.