Rachel Griffith, CBE FBA
Professor of Economics, University of Manchester
Research Director, Institute for Fiscal Studies
Laurens Cherchye, Bram De Rock, Rachel Griffith, Martin O'Connell, Kate Smith and Frederic Vermeulen "A new year, a new you? Temptation and self-control in food purchases"
The theoretical and behaviour literatures posit that consumers have self-control problems. We document that within-person (over time) variation in diet quality is large, as large as between-person variation. We propose a two-selves model in which food choices are a compromise between a healthy and unhealthy self, each with a well-behaved utility function. We used revealed preference tests to show that the data are consistent with this model. We recover the sharing rule, and use this to describe both variation in food preferences between people and quantify self-control problems using within-person variation.
Rachel Griffith, Martin O'Connell and Kate Smith "Temptation and Sugar Consumption"
We provide empirical evidence on the importance of temptation as a factor leading to poor nutritional choices. We do this by exploiting novel data that records the same consumers making decisions for immediate -- where temptation is likely to play a relatively stronger role for some consumers -- and future consumption. We consider choices made over non-alcoholic drinks: there are sugary and diet varieties of most brands and consumers may be tempted by the former. We incorporate the model in Gul and Pesendorfer (2001) into a random utility model of consumer choice among differentiated products (McFadden (1973), McFadden (1981) and estimate the model using longitudinal transaction level data. We show descriptively that the distribution of sugar purchases made for immediate consumption first order stochastically dominates the distribution of sugar purchases made for future consumption.