[isatrader]

What value do you put on Stan's momentum index (200d avg of NYSE ad line)? 

He says to look for divergence to spot ahead of time simple corrections (when divergance occurs over several weeks) or market crash (when divergence occurs overs months).

It's a long term indicator, and for the most part it spends a lot of it's time sideways. For me I tend to only take note when both the NYSE and Nasdaq momentum indexes either breakdown from very high levels, or both move below their zero lines at the same time. As to cover the majority of the US market you need to consider both the NYSE and Nasdaq data as a whole imo.

But in general you shouldn't worry about what a single indicator is doing and should always look at the "Weight of Evidence" from all of the breadth indicators as a whole. Stan is famous for using more than 50 for his Weight of Evidence approach. So always focus on what the breadth as a whole is saying before considering changing your strategy imo.