The Employment Cost Index for wages and salaries is based on a comparison of the average wage rates for the same set of jobs across a three-month interval. Employment for the majority of the jobs remains the same over the three months. However, if the index were based solely on the jobs for which their number of workers decreased, it would have shown wage growth of over 50 percent from December 2001 to December 2011. Conversely, if the index were based solely on the jobs for which their number of workers increased, it would have almost no wage growth over the same ten years. Therefore, this article describes how the jobs are defined and chosen for the ECI sample, and it explores how such high wage growth for jobs losing workers, along with such low wage growth for jobs gaining workers, affects the growth in the Employment Cost Index for wages and salaries overall.