Contributions for the 21 cm temperature power spectrum using simulations (solid lines), built using simulation S1 for  ⟨ x_α ⟩  = 0.4 (z ~ 20.25). Dashed lines: expected errors. Dotted lines: expected errors assuming that P_μ⁴ is known. Solid lines from top to bottom are P_μ⁰ (green), P_μ² (red) and P_μ⁴ (blue).