They may also capture the experiences of adult survey respondents, providing guidance on the nature and prevalence of those respondents' food needs. In terms of measurement, existing systems do not tap children's perspectives on their own lives, nor do they flow from a conceptualization of food insecurity that is grounded in children's experiences, their roles within households, or the ways in which they make sense of their environments. Adult survey respondents tend to under-report child food insecurity, missing as many as half of children who, themselves report going hungry because there is not enough food [16]. In terms of delivery, these systems rely on household samples, which exclude children in institutional settings and homeless children, and can substantially under-represent them in highly vulnerable household situations (migrant workers, those living in urban slums, distant rural households, those living in refugee camps, multi-family or extended family households) [17].