Editing Average (section)

==Moving average==
{{main|Moving average}}

Given a [[time series]], such as daily stock market prices or yearly temperatures, people often want to create a smoother series.<ref>{{cite book | first1=George E.P. | last1= Box |first2=Gwilym M.| last2= Jenkins| title= Time Series Analysis: Forecasting and Control | edition= revised| publisher=Holden-Day |date=1976 | isbn=0816211043}}</ref> This helps to show underlying trends or perhaps periodic behavior. An easy way to do this is the ''moving average'':  one chooses a number ''n'' and creates a new series by taking the arithmetic mean of the first ''n'' values, then moving forward one place by dropping the oldest value and introducing a new value at the other end of the list, and so on. This is the simplest form of moving average. More complicated forms involve using a [[weighted average]]. The weighting can be used to enhance or suppress various periodic behavior and there is very extensive analysis of what weightings to use in the  literature on [[Digital filter|filtering]]. In [[digital signal processing]] the term "moving average" is used even when the sum of the weights is not 1.0 (so the output series is a scaled version of the averages).<ref>{{cite book | first=Simon | last= Haykin | title= Adaptive Filter Theory | publisher=Prentice-Hall |date=1986 | isbn=0130040525}}</ref> The reason for this is that the analyst is usually interested only in the trend or the periodic behavior.