Duplicate: every table, the same cards

In ordinary bridge, one evening you get good cards and the next you do not. Duplicate bridge removes that luck: every table plays the same deals, and you are compared only with the people who held the same cards as you.

That way a good result means good judgement, not a lucky hand.

The weekly deal sheet on Whetstone does the same for a family or a club: everyone plays the same four deals, then compares.