NTPsec

A-ntpsec-6-hour-stats

Report generated: Wed Oct 14 19:01:44 2026 UTC
Start Time: Wed Oct 14 13:01:44 2026 UTC
End Time: Wed Oct 14 19:01:44 2026 UTC
Report published: Wed Oct 14 12:01:55 PM 2026 PDT
Report Period: 0.2 days

Local Clock Time/Frequency Offsets

local offset plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Time Offset -2.483 -1.574 -1.078 0.005 1.006 1.406 1.830 2.084 2.980 0.623 0.002 µs -0.2 3.225
Local Clock Frequency Offset 125.244 126.236 127.121 130.035 132.828 133.453 134.308 5.707 7.217 1.695 130.022 ppb -0.08278 2.556

The time and frequency offsets between the ntpd calculated time and the local system clock. Showing frequency offset (red, in parts per million, scale on right) and the time offset (blue, in μs, scale on left). Quick changes in time offset will lead to larger frequency offsets.

These are fields 3 (time) and 4 (frequency) from the loopstats log file.



Local RMS Time Jitter

local jitter plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Time Jitter 0.426 0.510 0.573 0.807 1.150 1.334 1.518 0.577 0.824 0.176 0.824 µs 0.7027 3.61

The RMS Jitter of the local clock offset. In other words, how fast the local clock offset is changing.

Lower is better. An ideal system would be a horizontal line at 0μs.

RMS jitter is field 5 in the loopstats log file.



Local RMS Frequency Jitter

local stability plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter 153.000 184.000 213.000 296.000 399.000 452.000 557.000 186.000 268.000 57.581 298.510 10e-12 0.4465 3.252

The RMS Frequency Jitter (aka wander) of the local clock's frequency. In other words, how fast the local clock changes frequency.

Lower is better. An ideal clock would be a horizontal line at 0ppm.

RMS Frequency Jitter is field 6 in the loopstats log file.



Local Clock Time Offset Histogram

local offset histogram plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Offset -2.483 -1.574 -1.078 0.005 1.006 1.406 1.830 2.084 2.980 0.623 0.002 µs -0.2 3.225

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Local Temperatures

local temps plot

Local temperatures. These will be site-specific depending upon what temperature sensors you collect data from. Temperature changes affect the local clock crystal frequency and stability. The math of how temperature changes frequency is complex, and also depends on crystal aging. So there is no easy way to correct for it in software. This is the single most important component of frequency drift.

The Local Temperatures are from field 3 from the tempstats log file.



Local Frequency/Temp

local freq temps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 125.244 126.236 127.121 130.035 132.828 133.453 134.308 5.707 7.217 1.695 130.022 ppb -0.08278 2.556
Temp ZONE0 54.768 54.768 54.768 55.306 55.844 55.844 55.844 1.076 1.076 0.447 55.345 °C

The frequency offsets and temperatures. Showing frequency offset (red, in parts per million, scale on right) and the temperatures.

These are field 4 (frequency) from the loopstats log file, and field 3 from the tempstats log file.



Local GPS

local gps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
nSats 7.000 8.000 8.000 9.000 11.000 11.000 11.000 3.000 3.000 0.909 9.250 nSat 0.1747 2.456
TDOP 0.550 0.560 0.590 0.830 1.200 1.260 1.460 0.610 0.700 0.193 0.872 0.4139 2.347

Local GPS. The Time Dilution of Precision (TDOP) is plotted in blue. The number of visible satellites (nSat) is plotted in red.

TDOP is field 3, and nSats is field 4, from the gpsd log file. The gpsd log file is created by the ntploggps program.

TDOP is a dimensionless error factor. Smaller numbers are better. TDOP ranges from 1 (ideal), 2 to 5 (good), to greater than 20 (poor). Some GNSS receivers report TDOP less than one which is theoretically impossible.



Server Offsets

peer offsets plot

The offset of all refclocks and servers. This can be useful to see if offset changes are happening in a single clock or all clocks together.

Clock Offset is field 5 in the peerstats log file.



Server Offset 162.159.200.123

peer offset 162.159.200.123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 162.159.200.123 1.956 1.956 2.891 3.679 5.177 5.765 5.765 2.285 3.810 0.572 3.694 ms 1.023 6.613

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 169.229.128.134

peer offset 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 169.229.128.134 1.382 1.382 3.593 4.041 4.595 6.305 6.305 1.002 4.923 0.555 3.994 ms -1.357 15.14

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 173.8.172.33

peer offset 173.8.172.33 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 173.8.172.33 -1.579 -1.579 -0.511 1.780 4.859 5.152 5.152 5.370 6.731 1.634 1.928 ms 0.2554 2.386

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 50.116.42.84

peer offset 50.116.42.84 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 50.116.42.84 -0.044 -0.044 1.496 2.546 5.464 6.847 6.847 3.968 6.891 1.133 2.847 ms 1.083 5.357

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 52.10.183.132

peer offset 52.10.183.132 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 52.10.183.132 1.435 1.435 2.202 3.114 6.050 6.312 6.312 3.848 4.877 1.157 3.553 ms 0.6518 2.59

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 64.142.122.36

peer offset 64.142.122.36 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 64.142.122.36 1.236 1.236 1.689 3.415 3.705 3.871 3.871 2.016 2.635 0.530 3.283 ms -2.352 8.077

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 66.220.9.122

peer offset 66.220.9.122 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 66.220.9.122 0.663 0.663 2.936 3.448 3.907 4.185 4.185 0.971 3.522 0.416 3.396 ms -3.627 24.88

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset SHM(0)

peer offset SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(0) -131.809 -131.459 -131.228 -129.669 -128.174 -127.878 -126.786 3.054 3.581 0.885 -129.648 ms -0.09032 2.564

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset SHM(1)

peer offset SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(1) -2.484 -1.575 -1.079 0.006 1.007 1.407 1.831 2.086 2.982 0.624 0.002 µs -0.1995 3.22

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Jitters

peer jitters plot

The RMS Jitter of all refclocks and servers. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 162.159.200.123

peer jitter 162.159.200.123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 162.159.200.123 0.631 0.631 0.904 1.554 16.241 17.565 17.565 15.337 16.934 4.571 3.456 ms 2.037 5.557

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 169.229.128.134

peer jitter 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 169.229.128.134 0.437 0.437 0.851 1.802 4.808 13.405 13.405 3.957 12.968 2.010 2.195 ms 4.03 21.36

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 173.8.172.33

peer jitter 173.8.172.33 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 173.8.172.33 1.178 1.178 1.466 2.829 12.917 21.182 21.182 11.451 20.005 4.184 4.416 ms 2.329 8.256

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 50.116.42.84

peer jitter 50.116.42.84 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 50.116.42.84 0.772 0.772 1.115 1.895 20.570 61.371 61.371 19.455 60.600 10.425 5.729 ms 4.059 21.15

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 52.10.183.132

peer jitter 52.10.183.132 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 52.10.183.132 0.673 0.673 0.894 1.943 15.886 18.316 18.316 14.992 17.643 4.453 3.690 ms 2.25 6.656

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 64.142.122.36

peer jitter 64.142.122.36 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 64.142.122.36 0.547 0.547 0.625 1.192 5.708 13.569 13.569 5.083 13.022 2.008 1.882 ms 3.588 18.33

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 66.220.9.122

peer jitter 66.220.9.122 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 66.220.9.122 0.796 0.796 0.901 1.707 3.576 13.602 13.602 2.676 12.806 2.269 2.194 ms 4.21 20.37

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter SHM(0)

peer jitter SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(0) 0.031 0.046 0.080 0.364 1.028 1.212 1.623 0.948 1.166 0.280 0.426 ms 1.106 4.276

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter SHM(1)

peer jitter SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(1) 0.149 0.290 0.402 0.763 1.501 1.948 2.775 1.099 1.658 0.345 0.836 µs 1.217 5.161

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 125.244 126.236 127.121 130.035 132.828 133.453 134.308 5.707 7.217 1.695 130.022 ppb -0.08278 2.556
Local Clock Time Offset -2.483 -1.574 -1.078 0.005 1.006 1.406 1.830 2.084 2.980 0.623 0.002 µs -0.2 3.225
Local RMS Frequency Jitter 153.000 184.000 213.000 296.000 399.000 452.000 557.000 186.000 268.000 57.581 298.510 10e-12 0.4465 3.252
Local RMS Time Jitter 0.426 0.510 0.573 0.807 1.150 1.334 1.518 0.577 0.824 0.176 0.824 µs 0.7027 3.61
Server Jitter 162.159.200.123 0.631 0.631 0.904 1.554 16.241 17.565 17.565 15.337 16.934 4.571 3.456 ms 2.037 5.557
Server Jitter 169.229.128.134 0.437 0.437 0.851 1.802 4.808 13.405 13.405 3.957 12.968 2.010 2.195 ms 4.03 21.36
Server Jitter 173.8.172.33 1.178 1.178 1.466 2.829 12.917 21.182 21.182 11.451 20.005 4.184 4.416 ms 2.329 8.256
Server Jitter 50.116.42.84 0.772 0.772 1.115 1.895 20.570 61.371 61.371 19.455 60.600 10.425 5.729 ms 4.059 21.15
Server Jitter 52.10.183.132 0.673 0.673 0.894 1.943 15.886 18.316 18.316 14.992 17.643 4.453 3.690 ms 2.25 6.656
Server Jitter 64.142.122.36 0.547 0.547 0.625 1.192 5.708 13.569 13.569 5.083 13.022 2.008 1.882 ms 3.588 18.33
Server Jitter 66.220.9.122 0.796 0.796 0.901 1.707 3.576 13.602 13.602 2.676 12.806 2.269 2.194 ms 4.21 20.37
Server Jitter SHM(0) 0.031 0.046 0.080 0.364 1.028 1.212 1.623 0.948 1.166 0.280 0.426 ms 1.106 4.276
Server Jitter SHM(1) 0.149 0.290 0.402 0.763 1.501 1.948 2.775 1.099 1.658 0.345 0.836 µs 1.217 5.161
Server Offset 162.159.200.123 1.956 1.956 2.891 3.679 5.177 5.765 5.765 2.285 3.810 0.572 3.694 ms 1.023 6.613
Server Offset 169.229.128.134 1.382 1.382 3.593 4.041 4.595 6.305 6.305 1.002 4.923 0.555 3.994 ms -1.357 15.14
Server Offset 173.8.172.33 -1.579 -1.579 -0.511 1.780 4.859 5.152 5.152 5.370 6.731 1.634 1.928 ms 0.2554 2.386
Server Offset 50.116.42.84 -0.044 -0.044 1.496 2.546 5.464 6.847 6.847 3.968 6.891 1.133 2.847 ms 1.083 5.357
Server Offset 52.10.183.132 1.435 1.435 2.202 3.114 6.050 6.312 6.312 3.848 4.877 1.157 3.553 ms 0.6518 2.59
Server Offset 64.142.122.36 1.236 1.236 1.689 3.415 3.705 3.871 3.871 2.016 2.635 0.530 3.283 ms -2.352 8.077
Server Offset 66.220.9.122 0.663 0.663 2.936 3.448 3.907 4.185 4.185 0.971 3.522 0.416 3.396 ms -3.627 24.88
Server Offset SHM(0) -131.809 -131.459 -131.228 -129.669 -128.174 -127.878 -126.786 3.054 3.581 0.885 -129.648 ms -0.09032 2.564
Server Offset SHM(1) -2.484 -1.575 -1.079 0.006 1.007 1.407 1.831 2.086 2.982 0.624 0.002 µs -0.1995 3.22
TDOP 0.550 0.560 0.590 0.830 1.200 1.260 1.460 0.610 0.700 0.193 0.872 0.4139 2.347
Temp ZONE0 54.768 54.768 54.768 55.306 55.844 55.844 55.844 1.076 1.076 0.447 55.345 °C
nSats 7.000 8.000 8.000 9.000 11.000 11.000 11.000 3.000 3.000 0.909 9.250 nSat 0.1747 2.456
Summary as CSV file


Glossary:

frequency offset:
The difference between the ntpd calculated frequency and the local system clock frequency (usually in parts per million, ppm)
jitter, dispersion:
The short term change in a value. NTP measures Local Time Jitter, Refclock Jitter, and Server Jitter in seconds. Local Frequency Jitter is in ppm or ppb.
ms, millisecond:
One thousandth of a second = 0.001 seconds, 1e-3 seconds
mu, mean:
The arithmetic mean: the sum of all the values divided by the number of values. The formula for mu is: "mu = (∑xi) / N". Where xi denotes the data points and N is the number of data points.
ns, nanosecond:
One billionth of a second, also one thousandth of a microsecond, 0.000000001 seconds and 1e-9 seconds.
percentile:
The value below which a given percentage of values fall.
ppb, parts per billion:
Ratio between two values. These following are all the same: 1 ppb, one in one billion, 1/1,000,000,000, 0.000,000,001, 1e-9 and 0.000,000,1%
ppm, parts per million:
Ratio between two values. These following are all the same: 1 ppm, one in one million, 1/1,000,000, 0.000,001, and 0.000,1%
‰, parts per thousand:
Ratio between two values. These following are all the same: 1 ‰. one in one thousand, 1/1,000, 0.001, and 0.1%
refclock:
Reference clock, a local GPS module or other local source of time.
remote clock:
Any clock reached over the network, LAN or WAN. Also called a peer or server.
time offset:
The difference between the ntpd calculated time and the local system clock's time. Also called phase offset.
σ, sigma:
Sigma denotes the standard deviation (SD) and is centered on the arithmetic mean of the data set. The SD is simply the square root of the variance of the data set. Two sigma is simply twice the standard deviation. Three sigma is three times sigma. Smaller is better.
The formula for sigma is: "σ = √[ ∑(xi-mu)^2 / N ]". Where xi denotes the data points and N is the number of data points.
Skewness, Skew:
The skewness of a random variable X is the third standardized moment and is a dimension-less ratio. ntpviz uses the FIsher-Pearson moment of skewness. There are other different ways to calculate Skewness Wikipedia describes Skewness best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
Kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses standard Kurtosis. There are other different ways to calculate Kurtosis.
A normal distribution has a Kurtosis of three. NIST describes a kurtosis over three as "heavy tailed" and one under three as "light tailed".
upstream clock:
Any server or reference clock used as a source of time.
µs, us, microsecond:
One millionth of a second, also one thousandth of a millisecond, 0.000,001 seconds, and 1e-6 seconds.



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