RT Article T1 Circular data in political science and how to handle it JF Political analysis VO 18 IS 3 SP 316 OP 336 A1 Gill, Jeff A2 Hangartner, Dominik 1981- LA English YR 2010 UL https://krimdok.uni-tuebingen.de/Record/1912479745 DO 10.1093/pan/mpq009