I am an engineer in and i work in the AI industry. Nowdays the focus in AI is most in the trading markets. There is no faster way to monetarize the work than using it in trading markets. When the forex robots are developed they need to be tested for functionality. When such tests are conducted there is always need to specify the right out of sample period. That period may turn a bad forex robot into a good, or make a good look like bad one. There is also important rule for choosing the learn period and all that can lead to different results. The forex market is not the best environment for an AI but it is what it is.