Confounder

Part of speech: noun

Definitions

1. A factor that interferes with the association between two variables by influencing both of them
2. An external element that confuses the correlation between a dependent variable and an independent variable by acting on both
3. A variable that distorts the apparent effect between two other variables by affecting both of them

Etymology: The word began life as a sixteenth-century verb-to-noun relative of "confound," and its ancestry runs through Latin "confundere," meaning "to pour together" or "to mix up." That Latin verb was built from "con-" ("together") and "fundere" ("to pour"), so the original picture is of substances being poured into one another until they cannot be told apart. Latin "fundere" also gave English "fuse" and "foundry," which makes "confound" a distant cousin of molten metal. The noun came into English in the Middle English period, from Anglo-Norman "confondour" or Middle French "confondeur," both forms of an agent noun meaning "one who confounds." English speakers then attached their own "-er" ending to the verb "confound," so the word is a hybrid: a Latin-rooted stem with an English suffix. Its sense has narrowed over time from general confusion to the specific statistical meaning it carries today, where a hidden third variable creates the appearance of a link between two others.

Synonyms: confounding variable, factor