Trends in the measurement of σ₆₈. The distribution is divided into ten bins, each containing the same number of objects, based on the apparent magnitude in the i-band, z_p and z_s, in the left and right columns, respectively. These trends show the precision, in terms of the centralised scatter σ₆₈, in the W1 and W3 validation sets. The solid line represents cases where the training and validation samples use the same field, while the dashed line indicates training with W1 and validation with W3, or vice versa.