Quote from ar1zona:
Thanks mercury
I came up with a new sheet yesterday to test the aforementioned formula of percentage spread where I long the ratio when A1/A0 - B1/B0 < -x% and short the ratio when A1/A0 - B1/B0 > x% and get out when A1/A0 - B1/B0 = 0 where A0 and B0 are reference points
I tried to use prev close and today's opening prices for both A0 B0. Most of the pairs (that worked for many others, like ABX:GG, FDX:UPS, CTSH:CTXS, basically all the well known pairs) didn't work. Only 2-3 pairs show a little bit of profits over the last 3 months. I honestly don't know what's wrong with the system, seems to work for others.
Anyways I will play around with the high-low, high-open, and open-low thing and see if there's opportunity in that. What I can do is to get a mean and standard deviation of the spread as you said, and plot a average line and band around it. The only question is do I use a moving average when calculating high-low range or do I take a historical average and apply it for every day? If a moving average is used everyday there will be a gap and the band will tend to draw a big circle on the graph, if I use a fixed average then the band is two horizontal lines.