A secular trend is phenomenon that describes the consistency of a variable pattern over a long period of times. The consistency could either be an increase or decrease. It can be identified regardless of the season, because it has been stable over time. Secular trend is seen in epidemiology, business, growth and so on.
For example, in growth, for over a prolonged time, secular trend has been identified in the onset of puberty in both girls and boys. For the past two decades, puberty have been seen to have an early onset in boys and girls and this continues to increase with time.
