2.7 COMPONENT/CHARACTERISTICS OF TIME SERIES
According to Murray .R. Spiegel Metric Edition 1961, there are four characteristics or component of time series.
When these types of data is regarded by days, month or year, we would
find out that the variable under investigation is fluctuating from time
to time, the change or fluctuation are caused by composite force that is
constantly at work. The force has four components or features namely;
A trend (or secular trend)
Seasonal variation (or fluctuation)
Cyclical variation
Irregular variation or random
2.8 ANALYSIS OF TIME SERIES
The analysis is usually used to detect the pattern of changes in statistical information over regular interval of time.
These patterns are projected to arrive at an estimate for the future.
The time series analysis helps us to cope with future uncertainty.
SECULAR OR TREND: The trend is the general direction in which the time
plot appears to be moving. It is denoted T_t, it is said to be
containing trend if the mean of X_t varies systematically with time, the
systematic change could be linear, quadratic, exponential or function
in form.

(2) SEASONAL VARIATION: These are short term variation due to different circumstance that may prevail and effect result at certain period of year or days of the week, time of the day.
A series is said to have seasonal if it exhibit similar or identical pattern for corresponding period of successive year. Such movement are due to recurring event which take place annually.