Tempering Alloys — Elder Scrolls Online
200 rubedite ore is 20 refinements. ^ 20 = ~36% That is, more than a 1 in 3 chance that you will get no Alloy from refining 200 rubedite. Even though the return rate is 1 per 200 ore. 400 rubedite ore is 40 refinements. ^ 40 = ~13% So you had about a 13% of not getting an Alloy 40 times in a row. More than 1 in 8.