The width of one grid column on the standardized score scale,
1 / sd(forced positions) with the population standard deviation. This
is the equivalence-region half-width used for consensus verdicts: a
score contrast smaller than one grid column is not expressible in a
completed sort.
Examples
delta_grid(c(2, 3, 4, 5, 7, 7, 5, 4, 3, 2))
#> [1] 0.4268637
