one-tailed
UK[ˌwʌnˈteɪld]US[ˌwʌnˈteɪld]
adj
Of or relating to a statistical test for which the critical region is one-sided, so that it is designed to detect an effect in only one specified direction.
Morpheme Breakdown
one
tail
ed
one
single
tail
extreme end
ed
adjective suffix
Etymology
The term "one-tailed" is a modern compound, primarily used in the specialized field of statistics. It combines the numeral "one," denoting singularity, with "tail," a metaphor borrowed from the visual representation of a distribution curve where the extremities are likened to tails. The "-ed" suffix adjectivizes the compound, creating a term that literally means "having a single tail." This construction logically describes a hypothesis test that concentrates its critical region in just one extremity of the distribution, focusing the analysis on a predicted direction of effect, unlike its "two-tailed" counterpart.
Analysis
Structure: one (single) + tail (extreme end) + ed (adjective suffix)
- one: From Old English 'ān' (one, a single), of Germanic origin; related to Dutch 'een' and German 'ein'. Functions as a numerical root meaning "single".
- tail: From Old English 'tægl' (tail), of Germanic origin. In a statistical context, it refers to the extreme end of a probability distribution.
- ed: A suffix forming adjectives from nouns or other adjectives, from Old English '-ede', '-ode', '-ad'. In this compound, it indicates "having the characteristics of".
Examples
The researcher used a one-tailed test because the hypothesis predicted a specific increase in scores.
A one-tailed analysis has greater statistical power to detect an effect in the anticipated direction.
Choosing between a one-tailed and two-tailed test depends on whether the research question is directional.