Table 2.

Machine learning (ML) classifier type and reliability.

Prediction task	Firearm-related fatality	Mass shooting
Training data size, n	1142	1038
Holdout data size, n	286	256
Best ML classifier	Random forest	Random forest
F1-score: cross-validation, test data, mean (SD)	0.91 (0.017)	0.88 (0.012)
F1-score: holdout data	0.90	0.88