I appreciate the tech and effort that went into this, but the assessment criteria could maybe be given a few options to suit individual desires/needs.
(Plus I need one to tell me to stop standing too much, or standing but not moving maybe, after incurring some foot problems due to excessive standing desk use during covid lockdown)
However, my neighbour is a career academic with a PhD in human factors, and just last Friday was telling me he had been searching for statistical validation for twenty years that maintaining "good posture" while sitting was beneficial, and has yet to be able to come up with anything even vaguely statistically meaningful.
His take is, any sitting posture is bad for you, if maintained or preferred excessively.
Seems you are good however, as long as you change often enough to balance out or average out the various "curl up" and "stretch out/arching" positions.
This is unless you have a particular injury, or scoleosis etc and have certain positions you need to avoid.
Otherwise, just slouch around, but change semi regularly.
So it would be good if somehow it could tell you too much curl, too much arch/stretch, or too long in one position, instead of deviation from an absolute. But this starts getting complicated on first inspection.
The desire for "good" posture, along with many other things, falls into the category of "are you telling me something you know, or something that someone told you?".
Question everything.
