Assessing the internal validity of a household survey-based food security measure adapted for use in Iran

Background: The prevalence of food insecurity is an indicator of material well-being in an area of basic need. The U. S. Food Security Module has been adapted for use in a wide variety of cultural and linguistic settings around the world. We assessed the internal validity of the adapted U. S. Household Food Security Survey Module to measure adult and child food insecurity in Isfahan, Iran, using statistical methods based on the Rasch measurement model. Methods: The U. S. Household Food Security Survey Module was translated into Farsi and after adaptation, administered to a representative sample. Data were provided by 2,004 randomly selected households from all sectors of the population of Isfahan, Iran, during 2005. Results: 53.1 percent reported that their food had run out at some time during the previous 12 months and they did not have money to buy more, while 26.7 percent reported that an adult had cut the size of a meal or skipped a meal because there was not enough money for food, and 7.2 percent reported that an adult did not eat for a whole day because there was not enough money for food. The severity of the items in the adult scale, estimated under Rasch-model assumptions, covered a range of 6.65 logistic units, and those in the child scale 11.68 logistic units. Most Item-infit statistics were near unity, and none exceeded 1.20. Conclusion: The range of severity of items provides measurement coverage across a wide range of severity of food insecurity for both adults and children. Both scales demonstrated acceptable levels of internal validity, although several items should be improved. The similarity of the response patterns in the Isfahan and the U. S. suggests that food insecurity is experienced, managed, and described similarly in the two countries.