Correlation plots of T_peak for the 2₀₂ − 1₁₁ line corrected to a common distance of 200 pc assuming a linear scaling (top) and FWHM (bottom) of the cavity shock component vs., from left to right, L_bol, T_bol, M_env, n₁₀₀₀ and F_CO as presented in Table 1. Class 0 and I sources are coloured red and blue respectively. The number of sources and Pearson correlation coefficient are given at the bottom of each panel.