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Uncertainity in Tracker - Feb 16, 2014 at 3:35PM
Magda Moscoso
3 Posts

How can I know the uncertainity in a measure that I did with tracker, for example position or velocity?

Replies to Uncertainity in Tracker

Re: Uncertainity in Tracker - Feb 18 2014 12:33PM
Douglas Brown Avatar
Douglas Brown
161 Posts

Hi Magda,

There is no "automatic" way to estimate the uncertainty, but here are some factors to consider:

  • how carefully the points are marked (how do they differ when another student marks them , etc)
  • how clearly the positions can be seen on the video (are there changes in lighting, blurriness due to speed, etc?)
  • how accurately the video is calibrated (this is often the source of large discrepancies)

Plus there are many more...  You really have to consider each experiment individually and make uncertainty estimates based on the above. It always helps to repeat the experiment to see how much variation occurs from one to the next.


Re: Re: Uncertainity in Tracker - Mar 03 2014 6:17PM
Magda Moscoso
3 Posts

Thanks for your answer.

Re: Re: Uncertainity in Tracker - Mar 03 2014 6:19PM
Magda Moscoso
3 Posts

Can you give any idea to meassure the  accurately of the video?


Re: Re: Re: Uncertainity in Tracker - Aug 02 2014 3:05PM
Ami B
9 Posts

you can check the deviation of time measurments from the 1/FPS.
i.e. check how t is acturate.
if you have model   you can compare the measurements to the model ( x,y,vx,vy,ax,ay )

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