# Why edit data?

Correcting tracking errors

Sometimes EthoVision XT tracks a reflection instead of the subject, or confuses the nose-point and tail-base. If that occurs, you can correct such errors in the Track Editor screen.

Examples

▪Reflections in a water maze. EthoVision XT tracks accidentally a reflection next to the maze's border. There are “spikes” in the resulting track.

tip Make sure that light is not directed to the water surface. Watch the video tutorial Set up your test environment (Help > Video Tutorial).

▪Nose-tail base swaps. In experiments set to nose-tail base tracking, the nose-point could be detected as the tail-base, and vice versa. In the last sample of the following track, the two body points are inverted. The Track Editor offers some ways to correct such swaps.

tip Try out the Deep learning tracking technique, which is superior at finding the subject’s nose-point.

Notes

▪important The Edit Tracks function in EthoVision XT is only intended for minor changes of a few points. If you have many errors, there is a problem with your experimental set-up, trial control or detection settings, and you should correct those problems rather than try to manipulate the raw data. For example, if EthoVision XT tracks the arm of the operator who released the animal in the water maze, do one or both the following:

▪In the Trial Control Settings, select to start tracking a few seconds after the subject is detected in the arena.

▪ In the Detection Settings, set a maximum subject size.