Trend Analysis is the practice of collecting information and attempting to spot a pattern, or trend, in the information. In some fields of study, the term "trend analysis" has more formally defined meanings.
Although trend analysis is often used to predict future events, it could be used to estimate uncertain events in the past, such as how many ancient kings probably ruled between two dates, based on data such as the average years which other known kings reigned.
Project management 
In project management trend analysis is a mathematical technique that uses historical results to predict future outcome. This is achieved by tracking variances in cost and schedule performance. In this context, it is a project management quality control tool.
In statistics, trend analysis often refers to techniques for extracting an underlying pattern of behaviour in a time series which would otherwise be partly or nearly completely hidden by noise. A simple description of these techniques is trend estimation, which can be undertaken within a formal regression analysis.
Today, trend analysis often refers to the science of studying changes in social patterns, including fashion, technology and consumer behavior.
See also 
- Trend analysis tries to predict a trend like a bull market run and ride that trend until data suggests a trend reversal (e.g. bull to bear market). Trend analysis is helpful because moving with trends, and not against them, will lead to profit for an investor. "Trend analysis Definition" (2005), WebFinance, Inc., web: Investor-TA: defined as: a comparative analysis of a company's financial ratios over time.
- "SETA :: Office of Social & Economic Trend Analysis" (2006), Iowa State University (IAstate), web: SETA-TA.
- "Public Attitudes on Higher Education - A Trend Analysis, 1993 to 2003" (February 2004), John Immerwahr (Senior Research Fellow), Public Agenda (HigherEducation.org), web: HighEduc.
- Project Management Book of Knowledge, PMBOK, PMI, 1997, page 334.
- PMBOK Ready Reckoner Pages 7 and 8.