The leader of that study admits that this factor is stronger in smaller towns and doesn't apply to more urban areas saying "It'd be so tough to nail down what's up with Wal-Mart".[128] These findings are underscored by another study conducted in 2009 by the National Bureau of Economics that showed "large, negative effects" for competing businesses within 5 to 10 miles (8 to 16 km) of the newly opening big-box retailer.