PEST Analysis is used to assess the market environment for a business.
There are variations of the model which identify other factors, although some researchers argue that those additional factors are just aspects of the main four. Variations include reorganization of the letters (ESTP, STEP) or the addition of Legal, Environmental, Ethical, Legislative, International, Industry, or Demography (PESTLE, STEEP, STEPE, STEEPLED, PESTELI).
In his 1967 book, Scanning the Business Environment, Francis Joseph Aguilar identified four aspects of the external environment in which an industry operates: Economic, Technological, Political, Social (ETPS).
Other authors have reorganized the letters and added new categories over the years. The following articles include some of the variants.
Business Source Premier -- scroll down to Business Source Premier and select "Enhanced Business Searching Interface" and then Browse: Country Reports
Business Monitor International
EIU: Economist Intelligence Unit (content no longer available)
Icon Group International, Inc. (no longer included?)
IHS Global Insight, Inc.
MarketLine, a Datamonitor business
OECD: Organisation for Economic Cooperation & Development
PRS Group, Inc.
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