SMA (simple moving average) impressions, basically refers to the average amount of impressions that your post is experiencing, in a given time-period. 

Simple moving average is a term which originates in mathematics. 

A simple moving average (SMA) is an arithmetic moving average, calculated by adding recent closing prices, and then dividing that by the number of time periods in the calculation average. SMA is computed as follows:

This method can also be applied if you replace A, with number of impressions in a day, and n is representing the total number of days. 

A simple moving average will help you calculate the amount of impressions that your post are experiencing on average, in a pre-defined time-period. 

TL;DR: SMA views can be understood as a trend-line with both acceleration and de-acceleration factored in.

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The Shield team