TY - JOUR AU - Einav,Liran AU - Leibtag,Ephraim AU - Nevo,Aviv TI - Not-so-Classical Measurement Errors: A Validation Study of Homescan JF - National Bureau of Economic Research Working Paper Series VL - No. 14436 PY - 2008 Y2 - October 2008 UR - http://www.nber.org/papers/w14436 L1 - http://www.nber.org/papers/w14436.pdf N1 - Author contact info: Liran Einav Stanford University Department of Economics 579 Serra Mall Stanford, CA 94305-6072 Tel: 650/723-3704 Fax: 650/725-5702 E-Mail: leinav@stanford.edu Ephraim Leibtag U.S. Department of Agriculture FRED-ERS-USDA 1800 M Street, NW Rm. N2137 Washingron, DC 20036 Tel: 202-694-5349 Fax: 202-694-5662 E-Mail: eleibtag@ers.usda.gov Aviv Nevo Department of Economics Northwestern University 2001 Sheridan Road Evanston, IL 60208-2600 Tel: 847/491-8212 Fax: 847/491-7001 E-Mail: nevo@northwestern.edu AB - We report results from a validation study of Nielsen Homescan data. We use data from a large grocery chain to match thousands of individual transactions that were recorded by both the retailer (at the store) and the Nielsen Homescan panelist (at home). First, we report how often shopping trips are not reported, and how often trip information, product information, price, and quantity are reported with error. We focus on recording errors in prices, which are more prevalent, and show that they can be classified to two categories, one due to standard recording errors, while the other due to the way Nielsen constructs the price data. We then show how the validation data can be used to correct the impact of recording errors on estimates obtained from Nielsen Homescan data. We use a simple application to illustrate the impact of recording errors as well as the ability to correct for these errors. The application suggests that while recording errors are clearly present, and potentially impact results, corrections, like the one we employ, can be adopted by users of Homescan data to investigate the robustness of their results. ER -