ex: HDFCBANK has 36.6% weight in bank nifty and ICICI 15%, Kotak 14%, etc.. so I have taken the weightage in to consideration to build the advance and decline based on the underlying assets of bank nifty. generally Advance and Decline, is just an indicator that shows the actual difference b/w number of stocks that are moving up/down. so in this case my approach was different to the original one.
fyi.. this is not an price action indicator, its purely based on the movement of underlying assets.
we have another set of sophisticated indicators which tells about the Volume change in the underlying assets. but those are premium. so please let me know if you are interested to test them, I can give access for free(15 days)