Histograms showing the distribution of obscuration diagnostic ratios ( F _2–10 keV/ F _isotropic). Dark blue histogram represents the non-variable 12 μm sources, cyan reflects the X-ray variable 12 μm sources (X-ray fluxes are averaged for each source), red denotes the [O iii] sample and the gray shaded region illustrates the average value for Sy1s from (a) Heckman et al. (2005), log ( ) = 1.59 ± 0.49 dex, (b) Diamond-Stanic et al. (2009), log ( ) = 1.92 ± 0.60 dex, and (c) Gandhi et al. (2009), log ( F _2–10 keV/ F _MIR ) = −0.34 ±0.30 dex. The left facing arrows represent X-ray upper limits in (a)–(c) and right facing arrows illustrate the [O iv] upper limits in (b); these values are not included in the histogram.