The value of clean and correct data in case of technical analysis of any markets especially stock market cannot be over emphasized
. Error free data and speed of data is key to decision making process for any good trader.
Though people do not realize most of the institutional traders always end up taking faster and better decision then a investor who is trading on a net based terminal is because of the type of data they are handling and speed of data they are using. In Indian stock Market National Stock Exchange gives fast ticker data but as the cost of the same is higher or it requires a better skilled data management only few of the technical analysis software vendors provide the same.
Historical data too plays a very important role in identifying the trend as one needs to adjust the data for bonus, dividend and split. As the premise on which most of the analyst work is history and trends in prices repeats itself they try to look for patterns in a non corrected data not realizing that high and low generated in non corrected data would obviously lead to loss as the reason why they reached where they reached may not happen if the stock is not pregnant with a bonus or a split.
Unfortunately online traders in NSE and BSE who are at the beginners of technical analysis do not understand the same and fall prey to wrong signals and make loss and lose faith in technical analysis itself.Also the speed of data makes all the difference in intra day trading. People do not realize that if the ticker is even fraction of second slower the price action which they observe has already happened and their trying to capture the same by putting a trade would end up in losing on impact cost and at times they need to actually chase the price. There is nothing wrong in the system they have found and tried off market but the speed with which it is coming along.
If you are using Technical Analysis Software to trade stocks or commodities it is prudent for everyone to benchmark the data flow and quality before they make a decision to subscribe to the same.