Vortex indicator
The Vortex Indicator is a technical indicator invented by Etienne Botes and Douglas Siepman to identify the start of a new trend or the continuation of an existing trend within financial markets. It was published in the January 2010 edition of "Technical Analysis of Stocks & Commodities". Inspiration. The Vortex Indicator was inspired by the work of an Austrian inventor, Viktor Schauberger, who studied the flow of water in rivers and turbines. Etienne Botes and Douglas Siepman developed the idea that movements and flows within financial markets are similar to the vortex motions found in water. The Vortex Indicator  was also partly inspired by J. Welles Wilder's concept of directional movement, which assumes the relationship between price bars gives clues as to the direction of a market. Description. A vortex pattern may be observed in any market by connecting the lows of that market's price bars with the consecutive bars’ highs, and then price bar highs with consecutive lows. The greater the distance between the low of a price bar and the subsequent bar's high, the greater the upward or positive Vortex movement (VM+). Similarly, the greater the distance between a price bar's high and  the subsequent bar's low, the greater the downward or negative Vortex movement (VM-). Identifying a trend. On a chart, VI+ and VI− will be seen to intersect each other at a change of trend, and begin to diverge ever wider as the strength of a trend increases. When VI+ is larger and above VI−, the market is trending up. Conversely, when VI− is bigger and above VI+, the market is trending down. A trader should focus on the key trend change points of the Vortex Indicator (i.e. the crossing points of VI+ and VI−). When VI+ crosses above VI− , a long (buy) position is indicated. A short or sell position is suggested when VI− crosses above VI+. The published article also suggested further measures to ensure an effective trading strategy, for example, only entering a trade at the extreme high or low of the price bar that corresponds with a crossing of the Vortex Indicator. Calculation. The high, low and close values are required for any chosen stock, future, commodity or currency. These values may be 15-minute, hourly, daily, etc. If this process is repeated, the resulting VI21+ and VI21− can be drawn graphically to represent the  two lines of the Vortex Indicator. Practical application. The Vortex Indicator is simple to use as the only required inputs are the high, low and close of a price bar. Traders may use the Vortex Indicator on its own, in combination with other technical indicators to confirm a change of trend or as part of a larger trading system. In addition, the Vortex Indicator may be used for any: The inventors of the Vortex Indicator recommend using longer time frames and parameters in order to filter out false signals. If a trader does opt to use a very short time  frame, such as 5 minutes, this should be combined with a long parameter of 34 or 55 periods. Because of its universal applicability, the Vortex Indicator is suitable for both short term traders as well as longer term fund managers who may wish to identify larger macro trends within a market. Coding and strategies. The Vortex Indicator is available on most charting software. Some of these companies have suggested additional trading strategies to use in conjunction with the Vortex Indicator, including the implementation of a trailing stop and making use of supporting indicators in order to reduce the number of  false signals. Comparative studies. To test the Vortex Indicator against Welles Wilder's directional movement indicator (DMI), a portfolio of 38 of the most actively traded, full sized, futures contracts was created. These 38 futures included a number of index and financial futures, currencies, metals, energy futures and commodities like grains, oils and foods. The test period was from 3 January 1978 to 6 November 2009, using a 14-day parameter for both indicators. Over the entire test period, and also during the last 10 years, the Vortex Indicator showed a better performance than the DMI. However, using a similar  test based on 101 NASDAQ stocks, on a smaller sample (for the period 2 January 1992 to 14 August 2009), the DMI showed a better performance than the Vortex Indicator.