Distributions of the PAH shape parameters of the PAH galaxies. Left: PAH widths (Lorentzian half width at half maximum (HWHM) in the rest frame) of the PAH 6.2 μm (black) and the PAH 7.7 μm (red). The wavelength resolving widths of our instrument are subtracted from the measured widths in quadrature. When the PAH 6.2 μm is unresolved, the instrumental width is used to indicate the upper limit of the intrinsic width (filled histogram). Right: inter-band flux ratio of PAH 6.2 μm/PAH 7.7 μm. In both panels, corresponding measured parameters of the IRS starburst templates of Brandl et al. (2006; one template; dotted line) and Smith et al. (2007; four templates; dashed lines) are indicated by vertical lines.