A mean combines several measurements into one representative value by averaging them. In Network Time Protocol (NTP), means help estimate clock differences when every observation includes network delay and uncertainty. section 9.9.2 section 9.9
NTP uses means in two related ways:
- Several server responses contribute to a weighted mean of their differences, using 1 / θ² so slow servers have less influence. section 9.9.2
- A mean summarizes competing assertions rather than revealing an independently verified universal time. section 9.9.2
Averaging two offset estimates
Suppose the first timestamp pair gives an offset of 8 ms and the second gives 12 ms. Their mean is (8 + 12) / 2 = 10 ms. NTP uses this combined estimate while also calculating network delay δ; a large δ makes a reading less reliable. section 9.9.2
