NTPsec

ntp2.wiktel.com

Report generated: Tue May 12 10:53:01 2026 UTC
Start Time: Mon May 11 10:53:00 2026 UTC
End Time: Tue May 12 10:53:00 2026 UTC
Report Period: 1.0 days

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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 -19.923 -8.605 -5.361 0.461 3.616 5.178 9.156 8.977 13.783 2.723 0.005 µs -5.093 16.77
Local Clock Frequency Offset -14.139 -14.058 -13.956 -13.615 -13.305 -13.219 -13.172 0.651 0.839 0.218 -13.615 ppm -2.56e+05 1.626e+07

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 0.739 1.366 1.771 3.199 5.234 6.401 10.917 3.463 5.035 1.078 3.309 µs 15.81 54.12

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 1.303 2.185 2.823 4.940 7.843 9.455 15.076 5.020 7.270 1.551 5.089 ppb 19.36 68.03

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 -19.923 -8.605 -5.361 0.461 3.616 5.178 9.156 8.977 13.783 2.723 0.005 µs -5.093 16.77

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats 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 132.163.97.5

peer offset 132.163.97.5 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 132.163.97.5 -1.421 -1.409 -1.393 -1.038 -0.990 -0.968 -0.958 0.402 0.441 0.125 -1.082 ms -924.9 9248

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 132.246.11.237

peer offset 132.246.11.237 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 132.246.11.237 195.640 251.639 292.168 569.209 787.477 952.758 1,014.849 495.309 701.119 182.599 531.776 µs 12.87 38.15

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 134.84.84.84

peer offset 134.84.84.84 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 134.84.84.84 -20.789 -17.652 -11.397 4.612 22.886 33.124 43.309 34.283 50.776 10.870 4.910 µs -1.46 4.23

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 204.9.54.119

peer offset 204.9.54.119 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.9.54.119 -1.037 -1.032 -1.027 -1.020 -1.012 -1.009 -1.003 0.015 0.024 0.005 -1.020 ms -9.907e+06 2.128e+09

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 2600:2600::99 (ntp1.wiktel.com)

peer offset 2600:2600::99 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2600:2600::99 (ntp1.wiktel.com) -365.403 -362.668 -357.480 -340.933 -326.662 -320.478 -314.283 30.818 42.190 9.273 -341.804 µs -5.439e+04 2.064e+06

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 2602:fd53:11e:123::1 (time1.mbix.ca)

peer offset 2602:fd53:11e:123::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2602:fd53:11e:123::1 (time1.mbix.ca) -438.473 -419.280 -404.976 -63.770 -8.168 7.580 15.553 396.808 426.860 174.447 -194.471 µs -15.92 48.85

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 2606:4700:f1::1 (time.cloudflare.com)

peer offset 2606:4700:f1::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2606:4700:f1::1 (time.cloudflare.com) -305.644 -230.658 -154.619 -25.881 73.885 153.080 254.722 228.504 383.738 69.286 -29.132 µs -7.332 22.49

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 2607:f388::123:2 (ntp2.doit.wisc.edu)

peer offset 2607:f388::123:2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2607:f388::123:2 (ntp2.doit.wisc.edu) -327.388 -294.830 -182.638 -19.429 17.461 30.892 44.170 200.099 325.722 61.825 -34.622 µs -11.35 50.12

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) -19.924 -8.606 -5.362 0.462 3.617 5.179 9.157 8.979 13.785 2.724 0.005 µs -5.093 16.76

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 132.163.97.5

peer jitter 132.163.97.5 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 132.163.97.5 10.617 15.098 20.147 54.275 357.850 385.666 405.417 337.703 370.568 131.052 144.090 µs 0.8429 1.84

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 132.246.11.237

peer jitter 132.246.11.237 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 132.246.11.237 0.051 0.088 0.131 0.356 1.391 8.312 13.783 1.260 8.224 1.246 0.605 ms 5.338 45.47

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 134.84.84.84

peer jitter 134.84.84.84 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 134.84.84.84 2.230 3.575 4.048 6.696 12.892 17.417 21.113 8.844 13.842 2.882 7.348 µs 9.807 35.02

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 204.9.54.119

peer jitter 204.9.54.119 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.9.54.119 2.584 3.177 4.873 9.178 16.192 20.503 23.847 11.319 17.326 3.428 9.691 µs 12.43 41.58

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 2600:2600::99 (ntp1.wiktel.com)

peer jitter 2600:2600::99 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2600:2600::99 (ntp1.wiktel.com) 4.233 7.162 8.950 18.499 34.291 39.105 47.968 25.341 31.943 7.635 20.118 µs 9.788 29.49

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 2602:fd53:11e:123::1 (time1.mbix.ca)

peer jitter 2602:fd53:11e:123::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2602:fd53:11e:123::1 (time1.mbix.ca) 6.667 7.039 12.804 38.537 348.921 364.097 387.662 336.117 357.058 136.309 141.943 µs 0.5452 1.452

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 2606:4700:f1::1 (time.cloudflare.com)

peer jitter 2606:4700:f1::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2606:4700:f1::1 (time.cloudflare.com) 6.557 7.597 11.693 32.510 128.131 232.659 255.970 116.438 225.062 43.473 48.727 µs 2.395 9.006

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 2607:f388::123:2 (ntp2.doit.wisc.edu)

peer jitter 2607:f388::123:2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2607:f388::123:2 (ntp2.doit.wisc.edu) 5.871 7.756 10.789 19.263 34.624 42.755 72.306 23.835 34.999 7.722 20.604 µs 11.11 43.09

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) 0.121 0.675 1.091 2.968 6.930 9.419 20.502 5.839 8.744 1.869 3.329 µs 4.25 14.94

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 -14.139 -14.058 -13.956 -13.615 -13.305 -13.219 -13.172 0.651 0.839 0.218 -13.615 ppm -2.56e+05 1.626e+07
Local Clock Time Offset -19.923 -8.605 -5.361 0.461 3.616 5.178 9.156 8.977 13.783 2.723 0.005 µs -5.093 16.77
Local RMS Frequency Jitter 1.303 2.185 2.823 4.940 7.843 9.455 15.076 5.020 7.270 1.551 5.089 ppb 19.36 68.03
Local RMS Time Jitter 0.739 1.366 1.771 3.199 5.234 6.401 10.917 3.463 5.035 1.078 3.309 µs 15.81 54.12
Server Jitter 132.163.97.5 10.617 15.098 20.147 54.275 357.850 385.666 405.417 337.703 370.568 131.052 144.090 µs 0.8429 1.84
Server Jitter 132.246.11.237 0.051 0.088 0.131 0.356 1.391 8.312 13.783 1.260 8.224 1.246 0.605 ms 5.338 45.47
Server Jitter 134.84.84.84 2.230 3.575 4.048 6.696 12.892 17.417 21.113 8.844 13.842 2.882 7.348 µs 9.807 35.02
Server Jitter 204.9.54.119 2.584 3.177 4.873 9.178 16.192 20.503 23.847 11.319 17.326 3.428 9.691 µs 12.43 41.58
Server Jitter 2600:2600::99 (ntp1.wiktel.com) 4.233 7.162 8.950 18.499 34.291 39.105 47.968 25.341 31.943 7.635 20.118 µs 9.788 29.49
Server Jitter 2602:fd53:11e:123::1 (time1.mbix.ca) 6.667 7.039 12.804 38.537 348.921 364.097 387.662 336.117 357.058 136.309 141.943 µs 0.5452 1.452
Server Jitter 2606:4700:f1::1 (time.cloudflare.com) 6.557 7.597 11.693 32.510 128.131 232.659 255.970 116.438 225.062 43.473 48.727 µs 2.395 9.006
Server Jitter 2607:f388::123:2 (ntp2.doit.wisc.edu) 5.871 7.756 10.789 19.263 34.624 42.755 72.306 23.835 34.999 7.722 20.604 µs 11.11 43.09
Server Jitter SHM(1) 0.121 0.675 1.091 2.968 6.930 9.419 20.502 5.839 8.744 1.869 3.329 µs 4.25 14.94
Server Offset 132.163.97.5 -1.421 -1.409 -1.393 -1.038 -0.990 -0.968 -0.958 0.402 0.441 0.125 -1.082 ms -924.9 9248
Server Offset 132.246.11.237 195.640 251.639 292.168 569.209 787.477 952.758 1,014.849 495.309 701.119 182.599 531.776 µs 12.87 38.15
Server Offset 134.84.84.84 -20.789 -17.652 -11.397 4.612 22.886 33.124 43.309 34.283 50.776 10.870 4.910 µs -1.46 4.23
Server Offset 204.9.54.119 -1.037 -1.032 -1.027 -1.020 -1.012 -1.009 -1.003 0.015 0.024 0.005 -1.020 ms -9.907e+06 2.128e+09
Server Offset 2600:2600::99 (ntp1.wiktel.com) -365.403 -362.668 -357.480 -340.933 -326.662 -320.478 -314.283 30.818 42.190 9.273 -341.804 µs -5.439e+04 2.064e+06
Server Offset 2602:fd53:11e:123::1 (time1.mbix.ca) -438.473 -419.280 -404.976 -63.770 -8.168 7.580 15.553 396.808 426.860 174.447 -194.471 µs -15.92 48.85
Server Offset 2606:4700:f1::1 (time.cloudflare.com) -305.644 -230.658 -154.619 -25.881 73.885 153.080 254.722 228.504 383.738 69.286 -29.132 µs -7.332 22.49
Server Offset 2607:f388::123:2 (ntp2.doit.wisc.edu) -327.388 -294.830 -182.638 -19.429 17.461 30.892 44.170 200.099 325.722 61.825 -34.622 µs -11.35 50.12
Server Offset SHM(1) -19.924 -8.606 -5.362 0.462 3.617 5.179 9.157 8.979 13.785 2.724 0.005 µs -5.093 16.76
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.
kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of 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".
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 Pearson's moment coefficient of skewness. Wikipedia describes it best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
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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