Differences in tick data

[Trade$afe]

In teaching my students re how to use tick-based charts on Advanced Charting I have repeatedly had problems with my charts showing a price pattern with highs, lows, and times that differs from that of my students' charts. This makes it difficult to cultivate a consistent approach to trading set ups using tick bars vs time bars. Why can't we all see exactly the same information on our charts as we do with time bars?

Michael

[DuaneG]

Hi Michael,

In many cases, even the smallest difference between the computers of two separate users can affect the way in which the data is displayed. This is a short excerpt from an article in our Knowledge Base that discusses this issue in more detail.

"We time-stamp the quotes as they are received from the exchanges. These quotes are then sent to our tick servers to build our database for tick and interval charts. Records are processed within milliseconds of each other. Even so, it is possible that slight differences can occur across the various tick servers, resulting in a trade being moved up to the next bar."

"There's an additional factor to keep in mind as well. When you initially request a new chart, the data is supplied from our Tick Server and loaded onto your desktop. From that point forward, data is then streamed in from our Network and cached locally on your system. When you "refresh", all of the data on that chart is re-sent by our Tick Server and the cached data is cleared. If your PC clock is slightly fast or slow, this could also result in slight differences after a refresh."

[Trade$afe]

Thanx, Duane. Your response was pretty much as I expected. Therefore, since the main variable appears to be each PC's clock, is there a way to synch it to the server's clock so a user can approach the 'absolute' as closely as possible? I use atomic clocking (auto-synched) already, yet experience the variances I've previously described.

One thing bothers me: several times my students and I have noted a high or low in a price pullback on an intraday chart that differed from user to user. I can understand charts forming slightly differently due to time stamping, etc. but not absolute highs or lows in a price pattern (e.g., pullback). Why would this occur?

Thanx again,

Michael Guess

[DuaneG]

Hi Michael,

Thanks for the response. Being able to sync to an absolute time between your system, your students computers and our servers would be quite difficult to achieve.

I'm not sure if you are instructing from a real-time perspective, but if you were working from a historical standpoint, the Tick Dowloader would be a better option to pursue. While the real-time synching is a problem due to the points I outlined in my earlier post, the historical data is synched and the data displayed should match that of your students and to one another.

[Trade$afe]

We use a combination of live charts during market hours and after hours.

Are you suggesting we use the tick downloader to capture historical data from the day, then play it all back to review afterward? And if so, are you suggesting everyone's charts will then be perfectly in synch?

If so, then that has limited usefulness, as some of my classes take place in the evening after mkt hours when it would probably work. But during live trading this is not practical.

Any other solutions? Thanx for your help!

Michael

[Johnny]

Hi Both
I too have noticed that some ticks seem to get missed from intraday charts. I once had a trade stopped out, but the 5-minute chart did not show the price reaching my stop. When I switched to a tick chart, sure enough the chart showed that my stop had been reached. Back to 5 min chart (refreshed) and the bar then showed the low at my stop.
Is this difference between the 5 min chart and the tick chart something we should expect regularly?