Use a Lower Scale Classification

coarse_classification(y) reduces the 10 scales from y <- classification(x) to the 4 scales below.

• + positive effect: reference < lcl

• ~ no effect: min(threshold) < lcl < reference and reference < ucl < max(threshold)

• - negative effect: ucl < reference

• ? unknown effect: lcl < min(threshold) or max(threshold) < ucl

coarse_classification(y) reduces the 6 scales from y <- remove_sign(classification(x)) into 3 scales.