This is the Market Mean index. It is used to identify if the market is really trending or if it is range bound(random). In theory, a random sample will be mean reverting 75% of the time. This indicator checks to see what how much the market is mean reverting and converts it to a percentage. If the index is around 75 or higher than the price curve of the market is range bound and there is no trend from a statistical standpoint. If the index is below 75 this means the price curve of the market is in fact trending in a direction as the market is not reverting as much as it should if it were truly following a random/range bound price curve.