Bootstrap

A percentile bootstrap on the ratio of medians. Each resample draws as many values as the side holds, with replacement, from the sorted samples; the ratio is the median of the second side over the median of the first, in permille, rounded half up. The generator is xorshift64 (shifts 13, 7 and 17) seeded from the SHA-256 of both sorted samples, so the interval is a function of the stored data alone and no clock or system random is read.