The random variations in a time series, called the irregular component, are caused by factors that are
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Short-term, unanticipated and non-recurring
The irregular component is made up of fluctuations that cannot be accounted for or predicted, often caused by unforeseen events such as floods, natural calamities or a labour strike.
Such random variations are caused by short-term, unanticipated and non-recurring factors.
The other descriptions belong to the other components: long-term and smooth is the secular trend, repeating within each year is the seasonal component, and a period of more than one year is the cyclical component.