I watched one of the 12-hour coin tossing marathons.

They were sitting with their laptops and pressed a button for every result.

I wonder if human error can explain (at least part of) the deviation from 50/50:

* locations of the buttons they pressed on the laptops (they only pressed once per toss before enter, meaning the button represented same-side or other-side)

* remembering what the coin started out as may be harder (or easier, but probably harder) when the result is other-side

* other??

Need to repeat this amount of tosses but with a higher degree of supervision to be sure of the result.