Table 2.

Demographics in normal cases.

	Train (n = 23530)	Validation (n = 619)	Test (n = 619)	P value
Density				0.898
almost entire fat	837 (3.6)	27 (4.4)	18 (2.9)
scattered fibroglandular densities	4206 (17.9)	106 (17.1)	115 (18.6)
heterogeneous dense	16434 (69.8)	432 (69.8)	432 (69.8)
extremely dense	2053 (8.7)	54 (8.7)	54 (8.7)
Age				0.997
≥50	14533 (61.8)	383 (61.9)	383 (61.9)
<50	8997 (38.2)	236 (38.1)	236 (38.1)
Manufacturer				0.4872
GE	11526 (49.0)	284 (45.9)	315 (50.9)
Hologic	10191 (43.3)	282 (45.6)	257 (41.5)
Siemens	1813 (7.7)	53 (8.6)	47 (7.6)