Rao 6a varieties of measurement for food security


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Rao 6a varieties of measurement for food security

  1. 1. FOOD SECURITY Concepts, Basic Facts,and Measurement Issues June 26 to July 7, 2006 Dhaka, Bangladesh
  2. 2. Rao 6a: Varieties of Measurement for Food Security: Classes + SourcesLearning: The session will introduce trainees to thestrategic choice of alternative indicators or measurementsof various dimensions and outcomes of FS or FIS basedon purposes, data and monitoring constraints, and needfor informational feedback to policy-makers.
  3. 3. Brief Contents• measurement approaches (economic, nutritional, anthropometric; secondary data, surveys, qualitative or subjective approaches)• relating measurement to policy purpose and data availability• starting with the object of measurement, identifying strengths and weaknesses of alternative measures• classes of FS measures, and their uses, data demands and ease of use: food access, dietary status, nutritional status, food utilization, health status• assessing options by their consistency and appropriateness to different situations, demands of FS monitoring entailed, underlying FIS causes, etc.
  4. 4. FS Concepts: A Reminder• FS exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life. Household FS is the application of this concept at the family level, with individuals within HH as the focus of concern.• FIS exists when people are undernourished as a result of the physical unavailability of food, their lack of social or economic access to adequate food, and/or inadequate food utilization.• Food-insecure people have food intake below their minimum calorie (energy) requirements, as well as those who exhibit physical symptoms caused by energy and nutrient deficiencies. An alternative view confines FIS to the consequence of inadequate consumption of nutritious food, leaving the body’s utilization of food as being within the domain of nutrition and health.• Vulnerability refers to the full range of factors that place people at risk of becoming food-insecure. The degree of vulnerability of individuals, HH or groups of people is determined by their exposure to the risk factors and their ability to cope with or withstand stressful situations.
  5. 5. First- & Second-Order Concerns• Note that FS is broadly defined as access to necessary food for good performance and health. This first-order definition, though important, does not fully capture all aspects of food requirements.• Second-order concerns based on measures of access and use describe in more detail the food situation of the population and of vulnerable segments of the population.• Different measures of food security are required in order to address these varied aspects of food security (in the broad sense used here).• There is no “magic bullet” or single measure that can possibly capture these different aspects of food security
  6. 6. Measurement Approaches• Alternative measures of FS exist with their own strengths and weaknesses.• Specific measures can be grouped broadly under the following heads: economic, nutritional, anthropometric; secondary data, surveys, qualitative or subjective approaches• Alternatives must be judged in terms of closeness with which the (1) concepts involved are captured as well as the (2) policy purpose at hand.• In practice, (3) data availability and (4) the costs of measurement also influence choice of measures.
  7. 7. Measurement Approaches (contd)• The complexities of measuring FS arise from the fact that FIS is a complex phenomenon. It is attributable to a range of factors that vary in importance across regions, countries and social groups, as well as over time.• The figure following illustrates this complexity with reference to the determination of one key aspect of FS i.e., nutritional status.
  8. 8. Framework for Understanding Nutritional status
  9. 9. Four Areas of VulnerabilityThe factors appearing in the Figure can be grouped in four clusters representing the following four areas of potential vulnerability: * the socio-economic and political environment; * the performance of the food economy; * care practices; * health and sanitation.
  10. 10. Objects of MeasurementAny system can be measured in two ways:• measurements can be made of the state of any part of the system; or• measurements can be made of flows through the system.Alternatively, indicators can be divided into• indicators of process; and• indicators of outcome.The figure following contains a representation of the food system, showing important objects of measurement – both flow indicators and indicators of system states.
  11. 11. Food System Indicators
  12. 12. States and Flows• Flow variables include size and distribution of incomes, food supply as shown by food balance sheets, HH food consumption and individual food intake.• Stock or situation or state variables are national food stocks, HH food stocks, HH conditions for food preparation and storage, clinical signs of malnutrition and anthropometric measurements. Some variables describe the macroeconomy, e.g., income distribution & food supply, others relate to the household e.g., food stocks and food consumption, and yet others are indicators of individual status e.g., food intake and anthropometric measurements. Some give a direct picture of FS; others are more important for analysing factors which modify food use and availability.
  13. 13. Food Categories• Foods are traditionally categorised into eight groups: - cereals (millet, sorghum, maize, wheat...) - roots + tubers (manioc, yams, sweet potato, ...) - sugar and honey - fats ( butter, oil..) - fruits and vegetables - meat, offal, eggs and fish - milk and milk products - legumes (nuts, lentils, beans...)
  14. 14. Nutrients• Nutrients constitute the active elements of foods utilised in the bodys functioning.• They comprise proteins, fats, carbohydrates, vitamins, minerals and trace elements.• Foods contain some or all of these nutrients in variable proportions.
  15. 15. Nutritional Requirements• The expression nutritional requirements refers to the quantity of energy and of nutrients, expressed on a daily basis, necessary for a given category of individuals that will allow these individuals, when in good health, to develop and lead a normal life.• Nutritional requirements have been established on the basis of physiological studies (metabolic balances) and field epidemiological studies.• Requirements vary according to age, sex, body weight, level of activity and physiological status (e.g., pregnancy and lactation).• They are expressed as averages, taking into account individual variation.
  16. 16. Classes of FS Measures• The basic classes of measures of food security are: food availability, food access, dietary status, nutritional status, food utilization, and health status• These classes are progressively more difficult to define and measure. Dietary & nutritional status can be measured only with data on RNI and nutrient intake levels. Food utilization requires other, more complex norms relating to the environment in which food intake takes place, while health status depends on factors other than food intake.• The choice of class (or combination of classes) to be measured will depend on the policy purpose and consistency/accuracy desired as well as on data availability and costs of data collection.
  17. 17. Classes … (contd.)• Food availability can be measured in a number of ways: the broadest is food adequacy for the population or for particular segments of it. Does the nation, a segment of the population or an individual household have available a food supply that is adequate and in right proportions to feed itself?• Food access is the ability of HH or individuals to acquire adequate quantities of available foods. National availability may still leave segments of people unable to access it due to low income, unavailability of certain foods in particular regions or seasons, poor education regarding nutrition/health, and many other factors.
  18. 18. Classes … (contd.)• Dietary status is measured in a number of ways from surveys or simple observation. Educational interventions for FS are often in communicated in terms of diets. Dietary recommendations are a rather simple way to express deficiencies in food security and easy to communicate in programs related to interventions.• Nutritional status for households or individuals is measured from household data adjusted for different members (usually by energy requirements) and from individual intake surveys. The idea is to get the food data and transform it with the nutrient composition tables, and develop estimates that are compared to the recommended daily requirements or other measures or standards.
  19. 19. Classes … (contd.)• Ordinarily, these comparisons use the recommended daily requirements, but can as well be made within the sample by investigating the tails of the distributions of daily or usual daily intake.• Food utilization is informally defined as the way the human body makes use of nutrients in food. Hygiene, sanitation, water quality, health care, food safety and other environmental factors affect food utilization. In a way this measure links health status and food security. Utilization underscores the point that there are other factors than food intake that determine whether or not the population or segments of the population have “good’ nutritional status. Nutritional status is not all about food
  20. 20. Classes … (contd.)• Health Status (often measured from health surveys) relates to the longer term impacts of diet and other factors on health. Measures used to determine health are self reported, like days of sickness in a year, visits to doctors, or directly measured like height and weight and other anthropometric measures on surveyed respondents. More intrusive anthropometric measures are illustrated by such factors as assays from survey participant’s blood and analyses to tissue measurements on arms or other extremities of the body. Often the health surveys from different countries have measurements that are specific to known diseases in the nation.
  21. 21. Potential Data Bases• Aggregate Production & Consumption Data for Major Food Crops (food availability)• Household Food Consumption Surveys (both availability and diet composition at HH level; can be extended to include individual food intake and inferences about food utilization).• Consumer Expenditure Surveys (give expenditure on food and food types used for estimating CPI, also contain information relating to FS: with sufficient details on the food basket, can be used to estimate diet and nutritional status)
  22. 22. Potential Data … (contd.)• Individual Intake Surveys (food consumption among sampled individuals: used to estimate usual daily intake of foods and, with help of a food composition table, to translate the food intake into nutritional intake; these estimates are the closest available for measuring usual daily intake of nutrients)• Health Surveys (relevant to FS, contain intake, anthropometric and self-reported data; self- reported measures such as sickness can be linked to dietary status & utilization; anthropometric measurements can indicate long term
  23. 23. Potential Data … (contd.)• Rapid Assessment Surveys (can be used in natural disasters or other episodic events to assess temporary food consumption, nutrition or dietary status in approximate terms)• Food Frequency Surveys (to infer dietary status and food availability but can only be suggestive since they lack sufficient experimental control)• Nutrition Surveillance Surveys (to get rough approximation of nutrition status)
  24. 24. Summary of Food Security Measures and Survey Data Sets Used to Estimate Them Food Security Availability Access Dietary Nutrition Nutrition Health Measure/ Status Status Utilization Status Data Set Aggregate Production and X Consumption Household Food X (within X Consumption X X Surveys household) (prorated) Consumer Expenditure X X X X SurveysIndividual Intake Surveys X X X Health Surveys X X X XRapid Assessment Surveys X X Food Frequency Surveys X X X Nutrition Surveillance X X X X Surveys Special Food Consumption X X X Surveys
  25. 25. Assessing The Situation At Different Levels Of Aggregation• FBS gives aggregated picture of food flows in terms of average calorie and protein availability at national level.• Compared with RNIs, FBS can be used to assess supply adequacy. But this does not tell us much about actual access under the existing income and asset distribution.• Food Consumption Data taken from expenditure or budget data are a better measure of potential access to food. These tend, however, to be weak on coverage of non-monetary access to food, through social institutions and obligations or through subsistence production. Also an individual HH may consume less food than average because it has more small children or elderly people, or the family is genetically small in body weight.
  26. 26. Assessing The Situation At Different Levels Of Aggregation (contd)• Food Intake estimates give more accurate estimate of actual food intake than food consumption data. However, they are subject to the same problem of comparison with average standards or RNIs.• Anthropometric Data give a clearer indication of problems of poor nutritional status. The data are somewhat easier to interpret as to the existence of a problem, but do not indicate whether nutrient or food deficiencies are the major cause.