Question

What is a time series? What are the objectives of time series analysis? Distinguish between secular trend, cyclical, seasonal and irregular fluctuations

Answer 1

Answer:

Time Series :

In mathematics, a time series is a series of data points indexed in time order.

Most commonly, a time series is a sequence taken at successive equally spaced points in time.

Thus it is a sequence of discrete-time data.

Objectives of Time Series Analysis :

There are two main goals of time series analysis:

Identifying the nature of the phenomenon represented by the sequence of observations

Forecasting (predicting future values of the time series variable).

Secular trend :

Secular trend, which describe the movement along the term.

Cyclical Trend :

Cyclical fluctuations, which correspond to periodical but not seasonal variations;

Seasonal trend :

Seasonal variations, which represent seasonal changes.

Irregular fluctuations :

Irregular variations, which are other nonrandom sources of variations of series.