Bureaucratic category cutpoints become the thresholds researchers use for fuzzy-set membership.

Evidence

These 5 categories have substantive importance in that they determine eligibility for as well as assignment into different qualification groups. Persons in categories I (93rd to 99th percentile) and II (65th to 92nd percentile) are considered to be above average in trainability; those in category III (31st to 64th percentile) are considered about average; those in category IV (10th to 30th percentile) are designated as below average in trainability; and those in category V (1st to 9th percentile) are designated as markedly below average…. The threshold for full membership (.95) in the set of respondents with high AfQT scores was placed at the 93rd percentile, in line with the military’s designation of the lower boundary of their highest category; the crossover point (.5) was set at the 80th percentile; and the threshold for full nonmembership (.05) in the set of respondents with high AfQT scores was placed at the 65th percentile, the bottom of the military’s second-highest AfQT category. — Gary Goertz, Social Science Concepts and Measurement, 715

Categorization

• XREF: Links to Ragin’s fuzzy-set methods literature and to the book’s central argument that concept structure determines measurement.