List of metropolitan areas by population. One concept which measures the world's largest cities is that of the metropolitan area, which is based on the concept of a labor market area and is typically defined as an employment core (an area with a high density of available jobs) and the surrounding areas that have strong commuting ties to the core.
Average Costs. In treatment year 1, the average costs per patient diagnosed with PTSD ($8,300), TBI ($11,700), or both ($13,800) were much higher than the average costs for those with neither PTSD nor TBI ($2,400) (see Table 2 and Figure 3 on page 20).
Between treatment year 1 and treatment year 4, the average costs of care for PTSD and combined PTSD and TBI declined by 54 per-cent and 29 percent, respectively, but the average costs of TBI care decreased by only 12 percent during that period.