Sentence:  [p 56] The term <WSD>"collocation</WSD>" refers to the characteristic co-occurrence patterns of words, i.e., which words typically co-occur in corpus data (see Units A10.2 and C1). Collocates can be lexical words or grammatical words. <WSD>Collocations</WSD> are identified using a statistical approach. Three statistical formulae are most commonly used in corpus linguistics to identify significant <WSD>collocations</WSD>: the M1 (mutual information), "t" and "z" scores. / [p 159] In lexical studies <WSD>collocation</WSD> and semantic prosody/preference can only be quantified reliably on the basis of corpus data. 
Meaning of the word marked with <WSD> tags:  A sequence of words or terms that co-occur more often than would be expected by chance (i.e., the statistically significant placement of particular words in a language).