Simulated data from the GMF-based emissivity models with the observed emissivities from the catalog. All data are averaged over bins of 1 Kpc width, as indicated by the horizontal error bars. For the model data, the vertical error bars indicate the variance in the binned data. A lack of vertical error bar indicates the presence of only one data point in the bin. Shown is the synchrotron emissivity (y-axis) as a functionof the path length for each HII region (x-axis). The simulated data shown here is normalized with respect to the longer path lengths (>18 Kpc).