Accumulating measurements
For each measured value `s`, update the sums `m0 += 1; m1 += s; m2 += s*s;`. A measurement of 1.3 contributes 1, 1.3, and 1.69, respectively. section 16.4
The kth raw moment of a sample S is `m_k(S) = Σ(s^k)` over every value s in S. Thus m0 counts measurements, m1 sums their values, and m2 sums their squares. These are sums, not averages: the mean is m1/m0. Higher-order moments can also be used to compute statistics such as skew, which describes asymmetry. section 16.4
TAKEAWAY: Keep the moment sums needed for a statistic while collecting repeated measurements; divide by the sample count when a mean is required. section 16.4
