of or relating to the fourth degree
a curve describing such an equation or function.
notes: included in logit hazard models are quartic in time, industry dummy variables from job before spell, and region dummy variables for year of spell onset. all statistics are monthly and weighted. robust standard errors clustered by person identifier are used for p-value calculations. time until entry is calculated from 27 weeks into the long-term unemployment spell, 15 weeks into the intermediate-term unemployment spell, and 2 weeks into the short-term unemployment spell. long-term (lt) spell = unemployed for ≥27 weeks, intermediate-term (it) spell = unemployed for 15–26 weeks, short-term (st) spell = unemployed for 2–14 weeks, afqt = armed forces qualifying test, and asvab = armed services vocational aptitude battery. bls.gov