Most analysts should be familiar with price retracement levels acting as support or resistance between trends of similar degree. Gann taught his students to measure prior price ranges and divide them into 1/8ths and 1/3rds, these levels can act as support in a downtrend or resistance in an uptrend.

When a market reaches these levels and reverses, all the trader has to do to verify a trend change is to look for a clustering of time cycles on that day. Gann angles also determine time & price intersections. Figure - 8 shows the recent 2086 low in the SPI on July 17 achieving an exact 50% retracement and the March 11 post election panic low at 2158 was on a 37.5% retracement.