Definition of a Rolling or Moving Average

Date: 03/05/2004 at 13:53:37
From: Pam
Subject: Rolling Average

When someone says they have calculated a "rolling average," what 
exactly does that mean?  I cannot find the definition in any math 
books.

I assume that if you calculate a rolling average for a one year 
period, for example, it means taking January through December for the
first period and averaging that data, then taking February through
January for the next period and averaging that, then moving on to
March through February and so on.

Date: 03/05/2004 at 14:05:36
From: Doctor Douglas
Subject: Re: Rolling Average

Hi Pam,

Thanks for writing to the Math Forum.

Yes, that is exactly what it means.  The term "rolling average" is
used in the financial community.  In statistics and mathematics, the
term "moving average" is usually used.  You can read more about it here:

  Eric Weisstein's World of Mathematics -- Moving Average
    http://mathworld.wolfram.com/MovingAverage.html 

Please write back if you have any further questions.

- Doctor Douglas, The Math Forum
  http://mathforum.org/dr.math/