Standard deviation of the BAO peak scale as a function of the number of simulations used in the covariance estimate (upper panel). Open circles indicate the results corresponding to the standard method. Long and short dashed lines corresponds to the analytic formulae of Dodelson & Schneider (2013) and Percival et al. (2014). The black solid line indicates the error obtained when the ideal precision matrix is used. Coloured lines (from blue to red) show the results obtain by applying CT with different tapering scales. The black dot–dashed line show the CT results when a too small tapering parameter is used (T_p = 80 h⁻¹ Mpc).