I use eSignal in my work because it allows me to jump from indicator to indicator to different time frame to new symbol quickly. That is essential when your domain is everything that trades in all time frames. The data is another story but that is for another blog post.
Last night, as I told my subscribers this morning, I attended the monthly meeting of the Long Island Stock Traders Meetup Group and one of the speakers showed the S&P 500 using a default StockCharts.com chart. It about 2 seconds, I said under my breath, "that does not look so good." This a day after writing my Barron's column saying it looked OK using eSignal.
I know from my days as a technical analysis product manager with Tradecenter, Knight-Ridder Financial and Bridge that not all software is the same let alone not all the data. What data is excluded? When do you start the count? Where do you put pre- and post-market data? And for this blog post, what exactly is the formula for RSI?
The old saw "you can torture the data to say whatever you want" comes to mind.
I know when I see something funky - which I can usually tell after a quarter century of looking at charts - I run through several websites and even the exchange website to see who says what. The chart of the India ETF (INP) is the latest example of how three services show one thing and three show another.
The moral of this story is that you should probably use two different charting packages for your trading. You want them to show a few discrepancies from time to time to be sure you are getting different "opinions," too.