NTPsec

A-ntpsec-12-hour-stats

Report generated: Mon Sep 14 08:02:04 2026 UTC
Start Time: Sun Sep 13 20:02:04 2026 UTC
End Time: Mon Sep 14 08:02:04 2026 UTC
Report published: Mon Sep 14 01:02:15 AM 2026 PDT
Report Period: 0.5 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 -3.341 -2.209 -1.485 0.034 1.270 1.722 2.276 2.755 3.931 0.845 -0.017 µs -0.3453 2.99
Local Clock Frequency Offset 69.336 71.121 72.861 97.336 130.936 136.230 139.313 58.075 65.109 21.186 100.119 ppb 0.1784 1.535

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 0.516 0.659 0.788 1.129 1.588 1.855 2.167 0.800 1.196 0.244 1.151 µs 0.6007 3.779

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 187.000 247.000 287.000 399.000 545.000 619.000 766.000 258.000 372.000 79.282 405.658 10e-12 0.4933 3.454

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 -3.341 -2.209 -1.485 0.034 1.270 1.722 2.276 2.755 3.931 0.845 -0.017 µs -0.3453 2.99

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 69.336 71.121 72.861 97.336 130.936 136.230 139.313 58.075 65.109 21.186 100.119 ppb 0.1784 1.535
Temp ZONE0 56.382 56.382 56.920 57.996 58.534 59.072 59.072 1.614 2.690 0.623 57.738 °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.



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 1.943 2.338 3.174 4.427 5.026 5.742 5.757 1.852 3.405 0.677 4.244 ms -0.7731 3.682

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 2.178 2.370 3.418 4.711 5.213 5.643 6.029 1.796 3.273 0.648 4.511 ms -0.8839 4.016

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 -1.232 -1.064 -0.462 2.237 5.070 6.255 6.279 5.532 7.319 1.636 2.221 ms 0.1328 2.653

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 0.813 1.638 2.258 3.636 4.549 5.462 5.536 2.291 3.824 0.723 3.476 ms -0.2794 4.91

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 1.895 2.103 2.400 3.669 5.620 6.973 7.653 3.220 4.870 0.982 3.886 ms 0.8104 4.108

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 0.618 1.903 2.860 4.035 4.617 5.019 5.437 1.756 3.116 0.669 3.827 ms -0.9952 5.573

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 -0.085 1.873 3.069 4.139 4.773 5.740 5.996 1.704 3.867 0.731 4.015 ms -1.325 8.788

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) -135.408 -135.174 -133.539 -130.890 -128.871 -128.037 -127.027 4.668 7.138 1.408 -131.000 ms -0.5464 3.864

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) -3.342 -2.210 -1.486 0.035 1.271 1.723 2.277 2.757 3.933 0.846 -0.017 µs -0.3447 2.987

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 0.442 0.474 0.641 1.656 9.253 13.289 14.105 8.612 12.815 2.754 2.698 ms 2.372 8.489

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 0.178 0.229 0.583 1.728 11.699 14.150 16.507 11.117 13.921 3.035 2.762 ms 2.539 9.281

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 1.105 1.302 1.707 3.286 6.732 8.839 12.144 5.026 7.537 1.713 3.710 ms 1.486 6.425

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 0.329 0.340 0.488 2.075 11.020 13.764 16.002 10.532 13.425 3.288 3.438 ms 1.587 4.825

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 0.332 0.411 0.648 2.075 13.920 15.441 15.469 13.273 15.030 3.225 3.109 ms 2.62 9.572

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 0.611 0.644 0.811 2.094 7.014 11.824 18.224 6.203 11.181 2.406 2.838 ms 3.051 15.88

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 0.354 0.437 0.921 2.237 10.796 15.439 18.140 9.874 15.002 2.748 2.949 ms 3.024 13.34

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) 0.044 0.076 0.142 0.499 1.181 1.607 2.000 1.039 1.532 0.320 0.556 ms 1.121 4.63

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) 0.198 0.409 0.567 1.057 2.010 2.586 3.750 1.443 2.177 0.453 1.146 µs 1.104 4.713

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 69.336 71.121 72.861 97.336 130.936 136.230 139.313 58.075 65.109 21.186 100.119 ppb 0.1784 1.535
Local Clock Time Offset -3.341 -2.209 -1.485 0.034 1.270 1.722 2.276 2.755 3.931 0.845 -0.017 µs -0.3453 2.99
Local RMS Frequency Jitter 187.000 247.000 287.000 399.000 545.000 619.000 766.000 258.000 372.000 79.282 405.658 10e-12 0.4933 3.454
Local RMS Time Jitter 0.516 0.659 0.788 1.129 1.588 1.855 2.167 0.800 1.196 0.244 1.151 µs 0.6007 3.779
Server Jitter 162.159.200.123 0.442 0.474 0.641 1.656 9.253 13.289 14.105 8.612 12.815 2.754 2.698 ms 2.372 8.489
Server Jitter 169.229.128.134 0.178 0.229 0.583 1.728 11.699 14.150 16.507 11.117 13.921 3.035 2.762 ms 2.539 9.281
Server Jitter 173.8.172.33 1.105 1.302 1.707 3.286 6.732 8.839 12.144 5.026 7.537 1.713 3.710 ms 1.486 6.425
Server Jitter 50.116.42.84 0.329 0.340 0.488 2.075 11.020 13.764 16.002 10.532 13.425 3.288 3.438 ms 1.587 4.825
Server Jitter 52.10.183.132 0.332 0.411 0.648 2.075 13.920 15.441 15.469 13.273 15.030 3.225 3.109 ms 2.62 9.572
Server Jitter 64.142.122.36 0.611 0.644 0.811 2.094 7.014 11.824 18.224 6.203 11.181 2.406 2.838 ms 3.051 15.88
Server Jitter 66.220.9.122 0.354 0.437 0.921 2.237 10.796 15.439 18.140 9.874 15.002 2.748 2.949 ms 3.024 13.34
Server Jitter SHM(0) 0.044 0.076 0.142 0.499 1.181 1.607 2.000 1.039 1.532 0.320 0.556 ms 1.121 4.63
Server Jitter SHM(1) 0.198 0.409 0.567 1.057 2.010 2.586 3.750 1.443 2.177 0.453 1.146 µs 1.104 4.713
Server Offset 162.159.200.123 1.943 2.338 3.174 4.427 5.026 5.742 5.757 1.852 3.405 0.677 4.244 ms -0.7731 3.682
Server Offset 169.229.128.134 2.178 2.370 3.418 4.711 5.213 5.643 6.029 1.796 3.273 0.648 4.511 ms -0.8839 4.016
Server Offset 173.8.172.33 -1.232 -1.064 -0.462 2.237 5.070 6.255 6.279 5.532 7.319 1.636 2.221 ms 0.1328 2.653
Server Offset 50.116.42.84 0.813 1.638 2.258 3.636 4.549 5.462 5.536 2.291 3.824 0.723 3.476 ms -0.2794 4.91
Server Offset 52.10.183.132 1.895 2.103 2.400 3.669 5.620 6.973 7.653 3.220 4.870 0.982 3.886 ms 0.8104 4.108
Server Offset 64.142.122.36 0.618 1.903 2.860 4.035 4.617 5.019 5.437 1.756 3.116 0.669 3.827 ms -0.9952 5.573
Server Offset 66.220.9.122 -0.085 1.873 3.069 4.139 4.773 5.740 5.996 1.704 3.867 0.731 4.015 ms -1.325 8.788
Server Offset SHM(0) -135.408 -135.174 -133.539 -130.890 -128.871 -128.037 -127.027 4.668 7.138 1.408 -131.000 ms -0.5464 3.864
Server Offset SHM(1) -3.342 -2.210 -1.486 0.035 1.271 1.723 2.277 2.757 3.933 0.846 -0.017 µs -0.3447 2.987
Temp ZONE0 56.382 56.382 56.920 57.996 58.534 59.072 59.072 1.614 2.690 0.623 57.738 °C
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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