However, our near-IR observations are deep enough to detect young sources across the entire region. For this reason, analysis of the luminosity functions discussed in Section \[s:analysis:ss:klf\] were performed using extinction-limited samples.

![Above: K band brightness distribution for young stellar source candidates identified in the W3 region. Below: \[3.6\] brightness distribution. \[fig:ysobd\]](./f4a.eps "fig:"){width="5.5in"}\
![Above: K band brightness distribution for young stellar source candidates identified in the W3 region. Below: \[3.6\] brightness distribution. \[fig:ysobd\]](./f4b.eps "fig:"){width="5.5in"}

Spatial Distribution of Young Stellar Sources \[s:analysis:ss:ysodist\]
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In Figure \[fig:ysopos\] we illustrate the spatial distribution of YSO candidates in the W3 region, overlaid on an dust extinction map constructed with the optimized near-infrared excess method NICEST method of @Lombardi:2009aa. The YSO sources appear to be very well constrained to the three well known areas of the complex (namely IC 1795, W3-Main and W3(OH)).

Class I sources are mostly confined to the areas of high extinction: following the prescription of @Lada:2013aa, we found that over 80 percent of the Class I sources are located in high extinction regions ($A_V>7.0$ mag), and the surface density of Class I sources is linearly correlated with $A_V$ within $3<A_V<12$ mag. This is in very good agreement with other cluster forming 