The dictionary definition of trend is a general direction in which something is developing or changing, but there are other more focused definitions that might be more helpful for guiding data science. Two such definitions are from Salomé Areias, who studies social trends, and Eurostat, the official statistical agency in the European Union:
"A trend is the slow variation over a longer period of time, usually several years, generally associated with the structural causes affecting the phenomenon being measured." - EUROSTAT, official statistical agency in the European Union (http://ec.europa.eu/eurostat/statistics-explained/index.php/Glossary:Trend)
"A Trend is defined by a shift in behavior or mentality that influences a significant amount of people." - Salomé Areias, social trend commentator (https://salomeareias.wordpress.com/what-is-a-trend/)
We generally think of trends as nothing more than a long rise or fall in stock market prices. However, trends can also refer to many...