A comparison becomes unfair when one side gets its context removed.

Comparisons go wrong when one side keeps its context and the other loses it. A figure without its conditions gets set beside a figure with them, and the difference looks like a difference in performance rather than in circumstance. It is one of the easiest distortions to produce and one of the hardest to spot.

When two things are compared, check that both have been described at the same level of detail. If one comes with explanations and the other is a bare number, the comparison has already been tilted. Ask for the missing context before drawing any conclusion.