Use of the linguistic terms "prescriptive and descriptive" first occurred in the early 1900s. Linguist J.C. Nesfield published the "Outline of English Grammar" in 1908 to support his prescriptive, rule-centered theory on grammar and linguistics. His work details centuries-old fundamental rules of grammar as they pertain to parts of speech, sentence structure and spelling. He believed grammar was inflexible and unchanging -- rules governed linguistics. Nesfield used classical texts from Oxford and Cambridge to back his prescriptive approach. In 1965, descriptivist Norm Chomsky wrote "Aspects of the Theory of Syntax" after recording and studying English-speakers' linguistic patterns. He determined that syntax, underlying meanings, sentence structure and word placement affect grammar and language. The descriptive theory says that language is adaptable and rules of grammar aren't set in stone.
Descriptive usages are generally understood and don't need to be taught, especially to native speakers. Because descriptivists more easily accept change due to syntax modifications and cultural influences, they believe language is learned or understood, rather than taught. For example, you don't need to teach students that your voice goes down at the end of a statement and up at the end of a question. Similarly, you don't have to teach students that lying is dishonest and stealing is unjust. However, prescriptive rules must be taught and often involve value judgments, according to present-day linguistics professor Matt McGarrity at the University of Washington.
Prescriptive and descriptive theorists differ on their approach to instruction. Prescriptivists typically abide by traditional elements that strive to preserve long-lasting grammatical rules, word forms, processes, or behaviors, even if the rules are outdated. Descriptivists allow for change and are willing to forgo some rules to fit current norms, according to PBS. For example, descriptivists might allow students to use either "slow" or "slowly" to modify a verb because people often use the words interchangeably. However, prescriptivists would say "slowly" is the only form of the word "slow" that should be used as an adverb.
Even though descriptive and prescriptive theories generally apply to debates over linguistics and grammar, you can apply similar concepts to analysis in the business world. Analysts use the descriptive approach to study real-time data patterns, even if the patterns don't follow normal expectations. They believe cultural situations, economic factors, changes in behavior, and current consumer trends affect output, and thus, predictability. Conversely, prescriptive analysts rely on computer models, statistical analysis and structured data mining to examine information, according to InformationWeek magazine. They use data and numbers to predict trends.