Lexical analysis is the study of vocabulary of a discourse (richness of vocabulary, redundancies…). This technique of language analysis identifies lexemes (sequence of characters with an identified meaning). It enables the researcher to measure the number of words used.
Lexical analysis focuses non words rather than text. The next step is the syntax analysis.
This technique can be used on advertisement identifying semantic fields used by a population. Advertisers can use this semantic fields when the population in question is targeted.