Plummer p parameter derived from simulated extinction observations without noise. Different central densities are shown on different lines: 10⁴ (cm^-3) (uppermost frames), 10⁵ (middle frames), and 10⁶ (bottom frames). Symbols and colours denote the used method: method B (black square), method C (blue circle), and method D (red star). Stellar density is given on the x-axis, where 1 means a similar density as in the WFCAM observations of TMC-1N. The true p value (2, 3 or 4) used in the simulations is given on top of each column and also shown as a dashed line in the figures. The derived p value is marked in the figures for each simulated stellar density and method with scale on the y-axis.