Mass comparison

Mass comparison is a method developed by Joseph Greenberg to determine the level of genetic relatedness between languages. It is now usually called multilateral comparison. Mass comparison has been referred to as a "methodological deception" and is rejected by most linguists, and its continued use is primarily restricted to fringe linguistics. (Campbell 2001, p. 45)

Some of the top-level relationships Greenberg named are now generally accepted thanks to analysis with other, more widely accepted linguistic techniques, though they had already been posited by others (e.g. Afro-Asiatic and Niger–Congo). Others are accepted by many though disputed by some prominent specialists (e.g. Nilo-Saharan), while others are almost universally rejected (e.g. Eurasiatic, Khoisan and Amerind).