Include Centered Moving Average (CMA) and MAPE in the Smoothing options

[#1]

The ability to apply a centered moving average to a trended metric could save a huge amount of time for analysts. The current moving average implementation is not as useful as it could be. To quantify and report trends, an analyst has to retrieve the raw numbers, calculate the CMA, and then calculate the MAPE to see if the CMA period is viable. If SiteCatalyst could calculate a CMA based on user-supplied periods, and include the MAPE in the output, many hours of analysts' time would be freed for actual analysis rather than computation.