User's Manual

Table Of Contents
1. Freedom of head movement describes the volume in front of the tracker in which the user must have at least one of the eyes. The numbers are
specified parallell/orthogonal to screen surface, assuming eye tracker is at 20 degree angle to screen.
2. The degree-of-accuracy and precision over percentage-of-population numbers result from extensive testing across representatives of the whole
population. We have made use of hundreds of thousands of diagnostic images and performed tests on approximately 800 individuals with differ-
ent conditions, vision, ethnicities, everyday dust, smudges or blemishes around their eyes, with eyes out of focus, etc. This has resulted in a
much more robust and high performance eye tracking experience and a much more realistic representation of true performance across the
whole population, not just in a mathematically “ideal” scenario.
3. The “ideal” degree numbers are the previous standard of measuring accuracy and precision, both previously from Tobii and presently from all
eye tracking competitors. Though “ideal” numbers are useful to get a general feel about comparative quality and performance, they are not appli-
cable to real world usage in the same way as quantitative degree-of-accuracy and precision over percentage-of-population numbers based on
extensive testing across representatives of the whole population.
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Appendix D Technical Specifications
Tobii Dynavox I-Series User’s manual v. - en-US