The 2 words have 2 different meanings:
affect - definition of affect by the Free Online Dictionary, Thesaurus and Encyclopedia.
Usage Note: "Affect" and "effect" have no senses in common.
As a verb "affect" is most commonly used in the sense of "to influence" (how smoking affects health).
"Effect" means "to bring about or execute": layoffs designed to effect savings.
Thus the sentence "These measures may affect savings" could imply that the measures may reduce savings that have already been realized, whereas "These measures may effect saving" simplies that the measures will cause new savings to come about.
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