Irregular trends in a time series are caused by

(A) Epidemics

(B) Strikes

(C) Festival season

(D) Floods

Choose the correct answer from the options given below:

A time series is data collected over time, such as daily sales or monthly temperature. It consists of four types of movements:

Trend: Long-term direction (e.g., population growing over years)

Seasonal: Regular patterns repeating at fixed times (e.g., ice cream sales high every summer)

Cyclical: Wave-like patterns over long periods (e.g., economic boom and recession)

Irregular/Random: Unpredictable, sudden events

Irregular variations are caused by events that are not predictable, not regular, sudden and unexpected, and don't follow a pattern.

Epidemics are irregular variations. They cannot be predicted when they will happen and occur as sudden outbreaks.

Strikes are irregular variations. They are unpredictable labor actions that happen suddenly.

Festival season is a seasonal variation. Festivals happen at the same time every year (Christmas in December, Diwali in October/November). Since the timing is known in advance, this is predictable and therefore not irregular.

Floods are irregular variations. Natural disasters cannot be predicted exactly when they will occur.

The correct answer is (A), (B) and (D) only.