I have heard of systems based on RSI such as go long when the rsi is above 50 and sell when the rsi is below 50. When I see daily graphs of stocks in yahoo with the rsi indicator included, I can see a good correlation in terms of price and RSI. The RSI can stay above the 50 mark for several days.
However, when I watch this indicator in real time, it seems to oscilate in a wide range well above and below the 50 mark, which would trigger constant buy/sell signals. So, how do these systems work?