The reason they excluded it was because the data they were provided for those companies did not differentiate between workers in Seattle and workers outside. Th

The reason they excluded it was because the data they were provided for those companies did not differentiate between workers in Seattle and workers outside. That said the economics of hiring an extra shouldn't be significantly different for a big company. Costco and Starbucks probably have some wiggle room to cut down on the number of staff at a certain time. Also, to quote from the study: "as shown in Table 2, in Washington State as a whole, single-site businesses comprise 89% of firms and employ 62% of the entire workforce (which includes 2.7 million employees in an average quarter)" [2]."