The y-y plot was improved by including all materials and processes, compared to perovskite composition alone (Fig. ). The prediction distribution became similar shape to that of experimental PCE, and scatter plots were distributed roughly along the reference line, suggesting a successful regression (Fig. ). Even though, note that many plots are still far from the reference line. Error was defined as prediction minus experimental PCE. The distributions of prediction errors are shown in Fig. . They showed that the data in the region of lower PCE tended to be overestimated, and the data in the region of higher PCE tended to be underestimated, resulting in a negative slope in both the training and test dataset. Steeper slopes were observed in error plots of perovskite composition alone due to a more significant bias (Fig. ), and the inclusion of process information suppressed the steepness due to a smaller bias. This phenomenon, negative slope in error plot, was also observed in the regression of organic photovoltaics . The literature reported that fewer data in the range of lower PCE caused such error distribution, and the regression of perovskite solar cells may have fallen into the same situation. Please do not adjust margins Please do not adjust margins