Chapter 20- Opentuition notes You said and it is written that Trend is underlying patter of time series when short term fluctuations are ignored. My question arises that Trend do account for Long term fluctuations (Cyclical fluctuations)? In book, it is also saying that despite various fluctuation caused by seasonality (short term variations). And lastly, what about random (or residual) variations, do trend accounts for them or it also ignores it?