It is also known as trend series, is smooth, regular and long term variance of series, observed over a long period of time.
B.
SECULAR TREND COMPONENT
II.
Fluctuations are unaccountable, unpredictable or sometimes caused by unforeseen circumstances
C.
IRREGULAR COMPONENT
III.
Time series shows an oscillatory movement where period of oscillation is more than one year.
D.
SEASONAL COMPONENT
IV.
When time series captures the periodic variability in the data, capturing regular pattern of variability within one-year. The main cause can be climate change etc.
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