Grey1
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NASNastrader said:Paul, I just did a mini study on VWAP TF's. See my post # 217 today, I've also attached the same excel attachment below). I found the difference between 500 Tick data & 1 Min data to be 0.03 C. But the difference between 1 & 5 Mins was 0.27 C, using Realtick. So with Tick data being the most accurate, there is a possibility that with another 0.03 C error, the error in data could be as much as 0.30 C using 5 mins charts.. This error could be much less using Tradestation or eSignal, and others (I'm not sure).
Now eSignal may start it's data from the 1st tick (pre-market) - I think, which to me means that even though the data is in Mins., the root data could be in Ticks, thus making your 5 Min. data pretty accurate. I'm not sure about Tradestation. The only way is to verify 5 Min. data with 100 or 500 Tick Data for comparisons, which you've probably done.
(Edited) You are right, I just found an article for eSignal, where it states that after the 1st 1/2 hour VWAP is usually less than 2 cents between 1 and 5 min charts, I've attached the article.
Thanks for your reply
There are many other reasons for the difference but it is not worth wasting time on it. There are rules on short selling using the sell side programs which can make another 1-2 C difference depending on the size . If you ask me don't worry about few C here or there as to be quite honnest , the volume going through is not what it looks any way ( don't really want to open up another Price / Volume debate ) .
grey1
PS:- Theoretically the tick data are the most accurate ..