Abstract:

Product changes in manufacturing and storage are often time-dependent. Sometimes these changes are linear, sometimes cyclical and at other times chaotic. It is often not obvious that a time-dependent change is in fact occurring in some variable of interest. In this report we discuss methods for studying whether a trend exists and, if so, what the nature of that trend is. Data used to study this problem, observations collected sequentially over time, are referred to as a time series. Time series techniques can prove to be important in bringing to light underlying trends in data that may be evident through other techniques.