Defining a partition of the cloud of individuals into groups, one can calculate the midpoints of the various groups.
The total variance of the cloud of individuals can then be broken down to between<U+2013>within variances, i.e. variance between the groups partitioning the cloud, and variance within the groups
The ratio of the between-variance to the total variance is denoted by n2 (eta-square), and accounts for the percentage of variance 'explained' by the group-variable.
(see Le Roux & Rouanet 2010, p. 20ff, 69, 114)