Barcode scanners, introduced in the early 1970s, were a foundational process innovation in the grocery supply chain. By 1984 scanners had been installed in 10% of food stores in the U.S. Difference-in-difference analysis of city-level price data shows that scanners reduced prices of groceries by...

We analyze the effect of Wal-Marts entry into the grocery market using a unique store-level price panel data set. We use OLS and two IV specifications to estimate the effect of Wal-Marts entry on competitors prices of 24 grocery items across several categories. Wal-Marts price advantage over...