**2. Methods**

Each May since 1998 the US BLS has released occupational employment statistics (OES) for over 800 occupational groups, reflecting information collected in May of the preceding year [24]. From this OES data the median hourly wage for pharmacy technicians (US BLS OES code 29-2052) was collected for each year from May 1997 through May 2018 [25]. In addition to collecting median hourly wages for all pharmacy technicians, median hourly wages were also collected each year for pharmacy technicians employed in industry sectors, including chain and independent pharmacies, grocery store pharmacies, mass merchandise pharmacy, hospitals, and governmen<sup>t</sup> agencies. The percentage change in the US consumer price index (CPI) from May to May of each year from 1997 through 2018 was also gathered from US BLS [26].

Beginning with 1997, the actual median pharmacy technician hourly wage was multiplied by the percentage change in CPI over the next year to determine the expected median pharmacy technician hourly wage for the following year. This expected median hourly wage was then multiplied by the CPI for each subsequent year to determine the median hourly wage that would have been expected for each year from the base year through May 2018. The actual median pharmacy technician hourly wage for each following year was then compared to the expected median pharmacy technician hourly wage for that year as calculated above. This is demonstrated in Figure 1, in which, beginning with the actual median pharmacy technician hourly wage in 1997, expected median hourly wages for future years were calculated, and then comparisons were made to the actual median hourly wage pharmacy technicians had each year. The primary research hypothesis is that when these comparisons are made the di fference will be \$0, reflecting a balance in compensation paid to these employees and their ability and willingness to accept these wages in the market. Any di fferences found between the actual median hourly wage and the expected median hourly wage for any particular year is defined as a wage premium (wage premium = actual median hourly wage – expected median hourly wage). Wage premiums which occurred prior to 2018 were adjusted to reflect 2018 net present values. The adjusted wage premiums were then summed from the base year through 2018, and then divided by the number of years being analyzed to determine the mean wage premium experienced by pharmacy technicians for each year over the term being considered. In the example described in Figure 1, pharmacy technicians in the United States experienced a mean adjusted wage premium of \$1.99/hour between 1997 and 2018, meaning that the median hourly wage for pharmacy technicians who worked between these years was, on average, \$1.99/hour higher than would had been expected had their wages increased by the CPI each year.

Figure 2 describes changes in the median hourly wages from 2009 to 2018. Pharmacy technician median hourly wages in the United States decreased by an average of \$0.35/hour relative to what would have been expected had their median hourly wage increased by the CPI over that time.

**Figure 1.** Calculation of the Mean Annual Hourly Wage Premium for Pharmacy Technicians from Base-year 1997 to 2018.

**Figure 2.** Calculation of the Mean Annual Hourly Wage Premium for Pharmacy Technicians from Base-year 2009 to 2018.

This analysis was repeated for all base years from 1997 to 2017, resulting in ranges from one year (2017 to 2018) to twenty-one years (1997 to 2018). This analysis was also performed on subsets of data for pharmacy technicians working in chain and independent pharmacies, grocery store pharmacies, mass merchandise store pharmacies, hospitals, and for governmen<sup>t</sup> agencies. An analysis was also performed to evaluate the presence of wage premiums across all workers in all occupational groups in the United States.
