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TIME SERIES ANALYSIS

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Introduction

                A time series consists of numerical data collected observed or recorded at more or less regular intervals of time each hour, day, month, quarter or year, More specifically, it is any set of data in which observation are arranged in a chronological order, Examples of time series are the hourly temperature recorded at a locality for a period of year, the weekly prices of wheat in
Lahore, the monthly consumption of electricity in a certain town, the monthly total of passengers carried by rial,the quarterly sales of a certain fertilizer, the annual rainfall at Karachi for a number of year, the enrollment of students in a college or university over a number of year and so forth.
 
            The analysis of a time series is a process by which a set of observation in a time series in analyses.Time series analysis is rather a difficult topic but we shall limit our discussion to the basics of time series analysis

         The observation in a time series, denoted by Y1, Y2, . . ., Yt, . . .  are usually made at equally spaced points of time or they are associated with equal interval of time (t). Given an observed time series, the first step in analyzing  a time series is to plot the given series on a graph taking time intervals (t) along the X-axis, as the independent variable, and the observed values (Yt) on the Y-axis, as the dependent Variable . Such a graph Will show various  types of fluctuations and other point of interest .


           It is worthwhile  to note that the middle of the period is taken to represent the data for that period. For example, the yearly data corresponds to June 30 or July 1, the middle of a calendar yearly and monthly data to the middle of the month, i.e. the 15th
day of the month.

  

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