title: Reliability and validity of a short form household food security scale in a Caribbean community.
abstract: BACKGROUND
  We evaluated the reliability and validity of the short form household food security scale in a different setting from the one in which it was developed.
  
  
  METHODS
  The scale was interview administered to 531 subjects from 286 households in north central Trinidad in Trinidad and Tobago, West Indies. We evaluated the six items by fitting item response theory models to estimate item thresholds, estimating agreement among respondents in the same households and estimating the slope index of income-related inequality (SII) after adjusting for age, sex and ethnicity.
  
  
  RESULTS
  Item-score correlations ranged from 0.52 to 0.79 and Cronbach's alpha was 0.87. Item responses gave within-household correlation coefficients ranging from 0.70 to 0.78. Estimated item thresholds (standard errors) from the Rasch model ranged from -2.027 (0.063) for the 'balanced meal' item to 2.251 (0.116) for the 'hungry' item. The 'balanced meal' item had the lowest threshold in each ethnic group even though there was evidence of differential functioning for this item by ethnicity. Relative thresholds of other items were generally consistent with US data. Estimation of the SII, comparing those at the bottom with those at the top of the income scale, gave relative odds for an affirmative response of 3.77 (95% confidence interval 1.40 to 10.2) for the lowest severity item, and 20.8 (2.67 to 162.5) for highest severity item. Food insecurity was associated with reduced consumption of green vegetables after additionally adjusting for income and education (0.52, 0.28 to 0.96).
  
  
  CONCLUSIONS
  The household food security scale gives reliable and valid responses in this setting. Differing relative item thresholds compared with US data do not require alteration to the cut-points for classification of 'food insecurity without hunger' or 'food insecurity with hunger'. The data provide further evidence that re-evaluation of the 'balanced meal' item is required.
authors.affiliation: Department of Public Health Sciences, King's College London. martin.gulliford@kcl.ac.uk
authors.forename: Martin C
authors.initials: MC
authors.lastname: Gulliford
authors.forename: Deepak
authors.initials: D
authors.lastname: Mahabir
authors.forename: Brian
authors.initials: B
authors.lastname: Rocke
mesh_terms: D000328:Adult; D044383:Black People / Q000523:psychology; D017691:Caribbean Region; D005191:Family Characteristics; D005247:Feeding Behavior / Q000145:classification / Q000208:ethnology*; D005508:Food Deprivation; D005523:Food Supply / Q000145:classification* / Q000191:economics / Q000592:standards; D006801:Humans; D006815:Hunger / Q000145:classification; D008875:Middle Aged; D011203:Poverty / Q000145:classification / Q000208:ethnology; D011594:Psychometrics / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012923:Social Class; D011795:Surveys and Questionnaires; D014300:Trinidad and Tobago; D035501:Uncertainty; D014481:United States; D014675:Vegetables; D044465:White People / Q000523:psychology; D001741:Black or African American