Lift (statistical association)
The ratio of how often two things actually occur together to how often you'd expect them to occur together by chance alone, given how common each one is individually. A lift of 1.0 means no relationship; above 1.0 means the pair travels together more than chance predicts; below 1.0 means less.
Example
Chondroitin and Glucosamine are declared together 35.46x more often than chance would predict (995 products) -- the highest lift among the compound pairs we track that appear together in at least 100 products.