TIME SERIES ANALYSIS
INTRODUCTION when a nation, state, an institution or a business unit etc., intend to study the behaviour of some element, such as price of a product, exports of a product, investment, sales, profit etc., as they have behaved over a period of time, the information shall have to be collected for a fairly long period, usually at equal time intervals. Thus, a set of any quantitative data collected and arranged on the basis of time is called ‘Time Series’. Depending on the research objective, the unit of time may be a decade, a year, a month, or a week etc. Typical time series are the sales of a firm in successive years, monthly production figures of a cement mill, daily closing price of shares in Bombay stock market, hourly temperature of a patient. Usually, the quantitative data of the variable under study are denoted by y1, y2, ...yn and the corresponding time units are denoted by t1, t2......tn. The variable ‘y’ shall have variations, as you will see ups and downs in the...
