Which of the following can’t be a component of a time series?

Options

A. Seasonality
B. Cyclical
C. Trend
D. Mean

Answer

To determine which of the following options can't be a component of a time series, we will analyze each option provided:

1. **Seasonality**
2. **Cyclical**
3. **Trend**
4. **Mean**

### Step-by-Step Solution:

**Step 1: Understand the components of a time series.**
A time series is a sequence of data points typically measured at successive times, spaced at uniform time intervals. The main components of a time series include:
- **Trend**: The long-term movement in the data.
- **Seasonality**: Regular fluctuations that occur at specific intervals, such as monthly or quarterly.
- **Cyclical**: Fluctuations that occur at irregular intervals, often influenced by economic or business cycles.
- **Irregular**: Random or unpredictable variations.

**Step 2: Analyze each option.**
- **Option 1: Seasonality** - This is a recognized component of time series.
- **Option 2: Cyclical** - This is also a recognized component of time series.
- **Option 3: Trend** - This is a fundamental component of time series.
- **Option 4: Mean** - The mean is a statistical measure that summarizes data but is not considered a component of a time series.

**Step 3: Conclusion.**
Based on the analysis, the mean is not a component of a time series. Therefore, the answer is:

**Final Answer: Mean**