EPF analysis of the first three ¹³CO transitions observed from an MHD clump. Results are shown for five T_kin values around the reference value T_ref. The images show the χ² planes for noiseless observations but assuming 20% error estimates. The contours are drawn at χ² = 1 (blue contour) and χ² = 2 (cyan contour). The minimum χ² values (average over the three transitions) are quoted in the frames. The white dots correspond to the χ² minima for 50 noise realisations consistent with the 20% observational noise.