Introduction to Time Series Analysis
This chapter concerns various models for time series data. Such data, observed in time, are temporal data. Often by the phrase "time series" people mean temporal data observed at regular time intervals. The daily closing prices of a stock are a time series observed at regular intervals, namely, at the closing bell, marking the closing time of the exchange each trading day. Time-series plots are used in the control of manufacturing and service processes. The variable monitored may be, to mention a few diverse examples, the diameters of bolts, or the lengths of time to make deliveries to customers, or the concentation of salt in potato chips. A control chart is a time series chart with upper and lower limits indicated. In statistical process control, a time-series plot is also called a run chart. Control charts may also be based on moving averages, where the window is moved one point at a time.