sphericity.

1. A repeated-measures condition in which differences between every pair of measurement conditions have equal population variance.

2. The extent to which an object's three-dimensional shape resembles a perfect sphere.

3. A regression-error condition combining equal conditional variance with zero conditional correlation between different errors.

Use it for

Words that belong together

• assumption of sphericity
• violation of sphericity
• test for sphericity

On the page

The team tested sphericity before comparing the four repeated measurements.

Usage notes

Primary category: academic / formal / analytical. Lexical Type: Word. Forms: Usually uncountable for the conditions or degree of shape; plural sphericities for distinct conditions or measured degrees. Commonness: uncommon (editorial estimate; not a corpus frequency statistic). Legacy lexical fields mirror sense 1; numbered fields keep each relevant meaning separate. Research distinction: Three distinct verified uses: repeated-measures pairwise-difference variance, physical spherical shape, and regression covariance. Search excerpt verifies the repeated-measures condition; no unseen article content is claimed. Writing functions: statistical reasoning, methodological precision.