In statistics and business, a long tail of some distributions of numbers is the portion of the distribution having a large number of occurrences far from the "head" or central part of the distribution. The distribution could involve popularities, random numbers of occurrences of events with various probabilities, etc.
单词
statistics 英 [stə'tɪstɪks] 美 [stə'tɪstɪks] n. 统计；统计学；[统计] 统计资料
distribution 英 [dɪstrɪ'bjuːʃ(ə)n] 美 ['dɪstrə'bjʊʃən] n. 分布；分配
portion 英 ['pɔːʃ(ə)n] 美 ['pɔrʃən] n. 部分；一份；命运 vt. 分配；给…嫁妆
occurrence 英 [ə'kʌr(ə)ns] 美 [ə'kʌrəns] n. 发生；出现；事件；发现
probability 英 [prɒbə'bɪlɪtɪ] 美 ['prɑbə'bɪləti] n. 可能性；机率；[数] 或然率 复数 probabilities