Walmart Research Paper
I. Introduction
Wal-Mart is more than just another large company. It is the largest corporation in the world, with total revenues of $285 billion in 2005. It employs over 1.2 million workers in the United States, at about
3,600 stores.1 To put this in perspective, the Wal-Mart workforce represents just under 1 percent of total employment and just under 10 percent of retail employment in the United States. It exceeds the number of high school teachers or middle school teachers, and is just under the size of the elementary school teacher workforce. Wal-Mart is reported to be the nation’s largest grocer, with a 19 percent market share, and its third-largest pharmacy, with a 16 percent market share [6].
During the past two decades, …show more content…
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B sample: all observations in the A sample that also have complete data for the general merchandising retail subsector to which Wal-Mart belongs.
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General merchandising includes retail stores which sell a number of lines of merchandise, such as dry goods, apparel and accessories, furniture and home furnishings, small wares, hardware, and food. The stores included in this group are known as department stores, variety stores, general merchandise stores, catalog showrooms, warehouse clubs, and general stores. (See http://www.census.gov/epcd/ec97sic/def/G53.TXT, as of June 13, 2007).
Based on 1997 Census data, general merchandising makes up about 2.2 percent of all retail establishments, and 10.7 percent of all retail employment.
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Because the rules for whether or not data are disclosed depend on the size of the retail sector and the size distribution of establishments within it, sample selection is endogenous. We therefore emphasize results for the A sample, which includes nearly all counties and years. We use the B sample only …show more content…
However, constructing data for this subsector results in nearly two-thirds of county-year pairs being discarded because of non-disclosure, in which case endogenous sample selection can be severe.
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Unfortunately, we are often missing information on when Discount Stores converted to Supercenters, which is frequent in the latter part of the sample. All we know is the current store type. We also received data identifying a small number of stores (54, as of 2005) that closed. We return to this issue in some of our robustness analyses. This data set also indicated some store relocations within counties, which are treated as continuing stores because WalMart replaced smaller, older stores with larger ones in nearby locations.
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The measurement error corresponding to stores opening in January through early March of the previous year is less important in the IV estimation than in OLS estimation, because the IV estimation identifies the effect from the predicted probability of store openings rather than actual openings, and these predictions typically will not vary much between adjacent years.
Wal-Mart is more than just another large company. It is the largest corporation in the world, with total revenues of $285 billion in 2005. It employs over 1.2 million workers in the United States, at about
3,600 stores.1 To put this in perspective, the Wal-Mart workforce represents just under 1 percent of total employment and just under 10 percent of retail employment in the United States. It exceeds the number of high school teachers or middle school teachers, and is just under the size of the elementary school teacher workforce. Wal-Mart is reported to be the nation’s largest grocer, with a 19 percent market share, and its third-largest pharmacy, with a 16 percent market share [6].
During the past two decades, …show more content…
•
B sample: all observations in the A sample that also have complete data for the general merchandising retail subsector to which Wal-Mart belongs.
18
General merchandising includes retail stores which sell a number of lines of merchandise, such as dry goods, apparel and accessories, furniture and home furnishings, small wares, hardware, and food. The stores included in this group are known as department stores, variety stores, general merchandise stores, catalog showrooms, warehouse clubs, and general stores. (See http://www.census.gov/epcd/ec97sic/def/G53.TXT, as of June 13, 2007).
Based on 1997 Census data, general merchandising makes up about 2.2 percent of all retail establishments, and 10.7 percent of all retail employment.
9
Because the rules for whether or not data are disclosed depend on the size of the retail sector and the size distribution of establishments within it, sample selection is endogenous. We therefore emphasize results for the A sample, which includes nearly all counties and years. We use the B sample only …show more content…
However, constructing data for this subsector results in nearly two-thirds of county-year pairs being discarded because of non-disclosure, in which case endogenous sample selection can be severe.
20
Unfortunately, we are often missing information on when Discount Stores converted to Supercenters, which is frequent in the latter part of the sample. All we know is the current store type. We also received data identifying a small number of stores (54, as of 2005) that closed. We return to this issue in some of our robustness analyses. This data set also indicated some store relocations within counties, which are treated as continuing stores because WalMart replaced smaller, older stores with larger ones in nearby locations.
21
The measurement error corresponding to stores opening in January through early March of the previous year is less important in the IV estimation than in OLS estimation, because the IV estimation identifies the effect from the predicted probability of store openings rather than actual openings, and these predictions typically will not vary much between adjacent years.