In statistics, a moving average, also called rolling average, rolling mean or running average, is a type of finite impulse response filter used to analyze a set of datum points by creating a series of averages of different subsets of the full data set.
Given a series of numbers and a fixed subset size, the first element of the moving average is obtained by taking the average of the initial fixed subset of the number series. Then the subset is modified by "shifting forward", that is excluding the first number of the series and including the next number following the original subset in the series. This creates a new subset of numbers, which is averaged. This process is repeated over the entire data series. The plot line connecting all the (fixed) averages is the moving average. A moving average is a set of numbers, each of which is the average of the corresponding subset of a larger set of datum points.
Anyone who has spent any time in the Life industry quickly learns to understand the rolling average when calculating 'persistency.' But dumbarse commenters wouldn't know anything about that.
Daily tracking results are collected via telephone surveys of 500 likely voters per night and reported on a three-day rolling average basis. To reach those who have abandoned traditional landline telephones, Rasmussen Reports uses an online survey tool to interview randomly selected participants from a demographically diverse panel. The margin of sampling error for the full sample of 1,500 Likely Voters is +/- 3 percentage points with a 95% level of confidence.
Just for them, here's a hypothetical seven days polling using a three day simple rolling average. There is nothing in Rasmussen's notes to suggest the use of anything other than a simple rolling average. There is no suggestion it is a cumulative, weighted or modified rolling average. However, if anyone can produce evidence to the contrary, I'll stand to be corrected.
|Three day Rolling Average|
|Result||even||Obam +1||Obam +2||Rom+1||Rom+1|