Normalized distributions of χ ² for our study samples. The left panel shows comparative histograms of χ ² for the training and testing samples. The dotted vertical line shows the quality cut χ ² = 0.006, defined as 3σ levels from the minor distribution peak. The right panel shows the cumulative plot of χ ² per stellar region in the testing sample. The γ Velorum LCs could be more affected by systematic effects than other stellar regions. For example, the quality cut indicates that 30% of γ Velorum LCs are strongly dominated by systematics, while 10% of the LCs in other regions have this problem.