Lawofaverages

2 clues
It involves likelihoods
Supposition that things will even out over time
Similar answers:
Aaverages
Averages
Averagesize
Averagesout
Battingaverages
Beverages
Bowlingaverages
Coverages
Hotbeveragesarehot
Lawofaverages
Leverages
Lowaverages
Overages