Rather than select a single definition, Gledhill proposes that collocation involves at least three different perspectives: (i) co-occurrence, a statistical view, which sees collocation as the recurrent appearance in a text of a node and its collocates, (ii) construction, which sees collocation either as a correlation between a lexeme and a lexical-grammatical pattern, or as a relation between a base and its collocative partners and (iii) expression, a pragmatic view of collocation as a conventional unit of expression, regardless of form. These different perspectives contrast with the usual way of presenting collocation in phraseological studies. Traditionally speaking, collocation is explained in terms of all three perspectives at once, in a continuum: