. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "The JCMT Nearby Galaxies Legacy Survey - III. Comparisons of cold dust, polycyclic aromatic hydrocarbons, molecular gas and atomic gas in NGC 2403" . . . . . . . "We used Spitzer Space Telescope 3.6, 8.0, 70 and 160 \u03BCm data, James Clerk Maxwell Telescope HARP-B CO J= (3-2) data, National Radio Astronomy Observatory 12 m telescope CO J= (1-0) data and Very Large Array H i data to investigate the relations among polycyclic aromatic hydrocarbons (PAHs), cold (\u223C20 K) dust, molecular gas and atomic gas within NGC 2403, an SABcd galaxy at a distance of 3.13 Mpc. The dust surface density is mainly a function of the total (atomic and molecular) gas surface density and galactocentric radius. The gas-to-dust ratio monotonically increases with radius, varying from \u223C100 in the nucleus to \u223C400 at 5.5 kpc. The slope of the gas-to-dust ratio is close to that of the oxygen abundance, suggesting that metallicity strongly affects the gas-to-dust ratio within this galaxy. The exponential scale length of the radial profile for the CO J= (3-2) emission is statistically identical to the scale length for the stellar continuum-subtracted 8 \u03BCm (PAH 8 \u03BCm) emission. However, CO J= (3-2) and PAH 8 \u03BCm surface brightnesses appear uncorrelated when examining sub-kpc-sized regions." . . . . . . . . . . . . .