Components of Time Series
Time Series — Chapter 2, GSEB Class 12 Statistics
The Four Components
Every time series can be broken down into four components working together:
Quick Comparison
| Component | Period | Cause | Predictable? |
|---|---|---|---|
| Trend (T) | Years | Long-term growth/decline | ✓ Yes (general direction) |
| Seasonal (S) | Within year | Weather, festivals, schedule | ✓ Yes (repeats yearly) |
| Cyclical (C) | 3–7 years | Business cycles | ~ Partially |
| Random (R) | Unpredictable | Unexpected events | ✗ No |
Key distinction: Trend = gradual change over years. Seasonal = repeated pattern within one year. Cyclical = long waves over multiple years. Random = no pattern.
Key Takeaways
Key Takeaways
- Trend (T): long-term upward or downward movement over years.
- Seasonal (S): regular periodic fluctuations within a year (festivals, weather).
- Cyclical (C): wave-like patterns over 3–7 years (business booms/recessions).
- Random (R): unpredictable, irregular fluctuations — no pattern.
- Trend and Seasonal are predictable; Cyclical is partially predictable; Random is not.