Developed by William Blau, the Ergodic Candlestick Oscillator examines the average ratio of the day change versus the day's trading range. An n-day EMA of the close to open change is divided by an n-day EMA of the difference between the high and low. This ratio is then smoothed by a m-day EMA.
There are two parameters used with the ECO on StockFetcher. The first indicates the period used for averaging the day change and day range. The second period specifies the period for the EMA used on the ratio of the day change and range.
The basic idea behind this measure is that in cases where the stock is making positive net changes on large trading ranges, the ECO values will be positive. In cases where the stock is trading lower each day, the ECO will be negative.