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.
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 behavior in a time series which would otherwise be partly or nearly completely hidden by noise. If the trend can be assumed to be linear, trend analysis can be undertaken within a formal regression analysis, as described in Trend estimation. If the trends have other shapes than linear, trend testing can be done by non-parametric methods, e.g. Mann-Kendall test, which is a version of Kendall rank correlation coefficient. For testing and visualization of nonlinear trends also smoothing can be used.
Trend analysis in text analysis
Trend analysis can be also used for word usage, how words change in the frequency of use in time (diachronic analysis), in order to find neologisms or archaisms. It relates to diachronic linguistics, a field of linguistics which examines how languages change over time. Google provides tool Google Trends to explore how particular terms are trending in internet searches. On the other hand, there are tools which provide diachronic analysis for particular texts which compare word usage in each period of the particular text (based on timestamped marks), see e.g. Sketch Engine diachronic analysis (trends).
- 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 ramping up in popularity because moving with trends, and not against them, will lead to profit for an investor. WebFinance, Inc., Investor-TA Trend analysis Definition: a comparative analysis of a company's financial ratios over time.
- Iowa State University Office of Social and Economic Trend Analysis.
- February 2004, John Immerwahr, Public Agenda, Public Attitudes on Higher Education – A Trend Analysis, 1993 to 2003.
- Project Management Book of Knowledge, PMBOK, PMI, 1997, page 334.
- PMBOK Ready Reckoner Pages 7 and 8.
- Kilgarriff, Adam; Herman, Ondřej; Bušta, Jan; Kovář, Vojtěch; Jakubíček, Miloš (July 2015). "DIACRAN: a framework for diachronic analysis" (PDF). Corpus Linguistics (CL2015). Corpus Linguistics 2015. United Kingdom: Lancaster University.