It not complicated. Nor is it a bias. Those are actual numbers out of your script.
On average, both methods require the same number of steps to reach a solution.
Noo,
If we take these metrics into account, it only means that, approximately within that key range, the prefix method achieved a higher success rate, which is highly significant.
dividing keys(avg) by wins, you'd determine the average success rate.
keys(avg)/wins = success_rate(avg)
I'm not sure what's unclear.
Over 10000 attempts, sequential method had to make 5,216,987,277 checks before finding 10000 solutions
Over 10000 attempts, prefix method had to make 5,224,672,888 checks before finding 10000 solutions
The number of checks is similar for both methods ?