Recovery of the input hyperparameters for simulations performed for a variety of 21 cm signal shapes. The peak-normalised histograms marginalised over all signal shapes, computed after subtracting the input values, are shown. The different panels correspond to the different hyperparameters. The results from the three runs of standard GPR are shown in different shades of blue, while the cross-GPR results are shown in red. A vertical line is plotted at Recovered = Input to indicate perfect recovery.