Working Paper: NBER ID: w14436
Authors: Liran Einav; Ephraim Leibtag; Aviv Nevo
Abstract: 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.
Keywords: measurement error; Homescan; validation study
JEL Codes: C81; D12
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| Recording errors in Homescan data (C83) | Inaccuracies in trip information (Z30) |
| Recording errors in Homescan data (C83) | Inaccuracies in price reporting (E30) |
| Matched trips (C78) | Alignment of quantity data between Homescan and retailer records (Y10) |
| Matched trips (C78) | Alignment of price data between Homescan and retailer records (C82) |
| Loyalty card discounts (L42) | Overreporting of prices in Homescan data (C82) |
| Correction methods for recording errors (C83) | Altered results in analysis of price paid with demographics (R20) |
| Systematic measurement errors (C83) | Sensitivity of analyses to household or trip characteristics (R20) |