Authors' response: Regarding the paper 'The impact of a supermarket nutrition rating system on purchases of nutritious and less nutritious foods' by Cawley et al. Issue 12 (17th December 2014) - Cawley, John; Sweeney, Matthew J.; Sobal, Jeffrey; Just, David R.; Kaiser, Harry M.; Schulze, William D.; Wethington, Elaine; Wansink, Brian