title: The inverse relationship between food price and energy density: is it spurious?
abstract: OBJECTIVE
  An important debate in the literature is whether or not higher energy-dense foods are cheaper than less energy-dense foods. The present communication develops and applies an easy statistical test to determine if the relationship between food price and energy density is an artifact of how the data units are constructed (i.e. is it 'spurious' or 'real'?).
  
  
  METHODS
  After matching data on 4430 different foods from the National Health and Nutrition Examination Survey with corresponding prices from the Center for Nutrition Policy and Promotion's Food Prices Database, we use a simple regression model to test if the relationship between food price and energy density is 'real' or 'spurious'.
  
  
  METHODS
  USA.
  
  
  METHODS
  Total sample size is 4430 observations of consumed foods from 4578 participants from the non-institutionalized US adult population (aged 19 years and over).
  
  
  RESULTS
  Over all 4430 foods, the null hypothesis of a spurious inverse relationship between food price per energy density and energy density is not rejected. When the analysis is broken down by twenty-five food groups, there are only two cases where the inverse relationship is not spurious. In fact, the majority of non-spurious relationships between food price and energy density are positive, not negative.
  
  
  CONCLUSIONS
  One of the main arguments put forth regarding the poor diet quality of low-income households is that high energy-dense food is cheaper than lower energy-dense food. We find almost no statistical support for higher energy-dense food being cheaper than low energy-dense food. While economics certainly plays a role in explaining low nutritional quality, more sophisticated economic arguments are required and discussed.
authors.affiliation: 1Department of Human Nutrition,Foods,and Exercise and Agricultural and Applied Economics,Virginia Tech University,214 Hutcheson Hall,Blacksburg,VA 24061,USA.
authors.forename: George C
authors.initials: GC
authors.lastname: Davis
authors.affiliation: 2US Department of Agriculture,Economic Research Service,Washington,DC,USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Carlson
mesh_terms: D000328:Adult; D003365:Costs and Cost Analysis; D016208:Databases, Factual; D004032:Diet / Q000009:adverse effects* / Q000191:economics; D004034:Diet Surveys; D030881:Disclosure; D002149:Energy Intake; D005523:Food Supply / Q000191:economics*; D006801:Humans; D008954:Models, Biological; D014481:United States; D016885:United States Department of Agriculture
keywords: Spurious