I also wrote to them but didn't receive any reply. So I finally called them today. A very short tempered East Indian guy with a heavy accent picked up the phone. Here's what he said: They have a formula which looks at the median price or ratio (price/SP500) for a set period of time (he said 2003 to present). using this period of time and the data based from it, they calculate to create a base line. He acknowledged that the base line does indeed move over time (every quarter when they redo the calculation). But he wouldn't go into what it actually is, saying its a 'big formula' and that its secret. This is sort of silly because it makes comparing the RS action over time impossible. Apparently this is a very old company (55+ years?) but it was bought out and some of the way they calculate things have changed. He wouldn't tell me when it was bought, or what was changed. He said that has nothing to do with the service they provide. I pointed out that if they've changed indicators, etc. that that would indeed effect their customers. No luck, they're about as forthcoming as MI6. Any quant jocks want to reverse engineer this? btw gummy, did you get a reply back? I'd like to compare notes.