Comparison of Techniques of Trend

Semi-Averages

Although simple to apply, the fact that only two plotted points are used in its construction leads to the general feeling that it is unrepresentative. It also assumes that a strictly linear Trend is appropriate to the data.

Least Squares

Although mathematically representative of the data, it assumes that a linear Trend is appropriate. It is generally thought unsuitable for highly ‘seasonal’ data.

Moving Averages

The most widely used technique for obtaining a trend. If the period of the averages is chosen appropriately, it will show a true nature of the trend, whether linear or non-linear. One disadvantage is that no trend values are obtained for the beginning and end time points of a series.