I suck at forum search-fu.. But I remember there was a scientific college study on "pip" dice- those rounded corner dice where the numbers are little dents dug out of the plastic- meaning the 6 has less physical plastic on its side than the 1 does.
Anyway, the end result was proven with like 1000 dice, each rolled 1600 times or whatever the proper number of statistical tries were.. that the 1 was rolled statisticly
more often than it
SHOULD have... something like 19% rather than the 16.6% it SHOULD have been. Further the 6 rolled less than they should- like 14%. They used super precise casino dice as a control to compare them to- and these indeed did 16.6% all the way across the numbers.
High speed cameras were used to watch their tumble, and they figured out why: youd think the 6 would be more common on top, since the 1 side is heavier and would settle at the bottom more often, but actually its the other way around, while rolling to a stop, the 1 on top has the most mass up there to
RESIST the next tumble- meaning that it will stop with the 1 on top more often than the others. CERTAINLY more than the 6, which was able to resist the final flop LEAST of all!
Some dice were aberrations- each die was rolled in its own little 'cubicle', so the ones that consistently rolled 1s were easy to keep track of.. and some dice rolled 1s at up to 24%!!!! [ACK! they
DO exist!!] These aberrations were cut in half to see what their issue was, and it was found that these dice had air bubble voids in their molded plastic- all dice had bubbles here and there, but the aberrations had more bubbles near the 6 than usual- further nudging the 1 result in the tumble roll to be more probable.
So, at the end of the study, it was determined that rounded corner pip dice were BAD for gaming if you want high numbers, good if you want low numbers. In effect- they were lousy gaming dice. The study recommended that rather than tumbling/scattering the dice, it would be better to rattle them in a cup/box, then flip the box over and letting the dice slam straight down - laying however they were juggled.
Rolling and letting them coast to a stop= bad. The statistical dice graduate study said so.
Reading this, or even better- finding the study itself- would make anybody a bit superstitious about dice.