Dr Mike said:
To me in seems that if you're speculating on a "bastardised" instrument and there is only one data source for it, then that is the one you use.
I've been reading this board for a couple of months now, and am planning to try a little spreadbetting in the near future. One recurring theme on this board (apart from bias, large spreads etc), is that you should trade off a different chart to the one provided by the SB company.
This struck me as being slightly odd. I am glad I am not the only one. It seems that trading off a different instrument believed to be the 'underlying' instrument is risky unless you know exactly how the SB instrument is derived. If you do know, then great - you can try to second guess a) what the market is doing, and b) how the SB company will adjust it's instrument in response, and c) how you should trade to take advantage of this extra information.
Failing that, trading off the SB chart is surely less risky than trying to second guess the SB's responses to the underlying instrument.
As long as the derived instrument broadly follows the underlying instrument, then it can be traded with the same basic rules. If this is true (and I suspect it is) then TA on the SB instrument should work quite nicely.
Spread and bias are basically irrelevant to this argument, since you are still trading with the SB company regardless of what you happen to be reading at the time. Your only 'free variable' is the time at which you enter/exit a trade. Now if anyone wants to claim that an SB company has delayed figures, I'm all ears!
-svengali