Dividing up my trades by time of day, I see that two specific hours of the day stand out as negative, whereas all others are positive. Is this something others have found, that their strategies simply don't work during certain parts of the day or is it random? Obviously, I will keep collecting data on it and perhaps it will turn out that over a longer run, the effect will go away, but I'm curious to hear from those who maybe have had a longer time to analyze this effect on their outcomes. I'm holding one key variable constant in this analysis, so that it is pretty apples to apples. The main thing I think of which could drive it is that the group of traders from whom my strategy takes profits simply aren't in the market during those specific times. Otherwise, it does strike me as arbitrary and not a legitimate rationale for filtering trades.