NTPsec

crane3.services.mbix.ca

Report generated: Mon Aug 24 16:45:02 2026 UTC
Start Time: Mon Aug 17 16:45:00 2026 UTC
End Time: Mon Aug 24 16:45:00 2026 UTC
Report Period: 7.0 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 -45.743 -23.297 -17.699 -3.158 28.241 39.618 72.403 45.940 62.915 13.952 -0.001 µs -3.052 6.984
Local Clock Frequency Offset 78.368 78.425 78.466 78.654 78.723 78.766 78.831 0.257 0.341 0.078 78.629 ppm 1.019e+09 1.026e+12

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 5.323 9.285 11.399 18.267 26.708 30.435 42.978 15.309 21.150 4.684 18.550 µs 35.19 136.6

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 2.284 3.513 4.220 6.557 9.261 10.593 16.714 5.041 7.080 1.568 6.630 ppb 43.76 180.4

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 -45.743 -23.297 -17.699 -3.158 28.241 39.618 72.403 45.940 62.915 13.952 -0.001 µs -3.052 6.984

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 78.368 78.425 78.466 78.654 78.723 78.766 78.831 0.257 0.341 0.078 78.629 ppm 1.019e+09 1.026e+12
Temp LM0 37.000 37.000 38.000 40.000 41.000 41.000 42.000 3.000 4.000 0.869 39.641 °C
Temp LM1 34.000 34.000 35.000 36.000 38.000 39.000 39.000 3.000 5.000 0.950 36.450 °C
Temp LM10 32.000 33.000 33.000 35.000 37.000 38.000 39.000 4.000 5.000 1.139 34.903 °C
Temp LM2 32.000 33.000 33.000 35.000 36.000 36.000 37.000 3.000 3.000 0.879 34.601 °C
Temp LM3 37.000 37.000 38.000 40.000 41.000 41.000 42.000 3.000 4.000 0.872 39.638 °C
Temp LM4 35.000 35.000 35.000 36.000 38.000 39.000 40.000 3.000 4.000 0.829 36.571 °C
Temp LM5 61.000 62.000 62.000 63.000 64.000 64.000 64.000 2.000 2.000 0.571 63.072 °C
Temp LM6 39.000 40.000 40.000 42.000 43.000 44.000 44.000 3.000 4.000 0.935 41.652 °C
Temp LM7 37.000 38.000 39.000 40.000 42.000 43.000 44.000 3.000 5.000 1.039 40.232 °C
Temp LM8 38.000 39.000 40.000 41.000 42.000 43.000 44.000 2.000 4.000 0.963 40.947 °C
Temp LM9 36.000 37.000 38.000 39.000 41.000 42.000 43.000 3.000 5.000 1.088 39.487 °C
Temp ZONE0 39.000 40.000 40.000 42.000 43.000 44.000 45.000 3.000 4.000 0.964 41.763 °C
Temp ZONE1 37.000 38.000 38.000 40.000 41.000 42.000 42.000 3.000 4.000 0.938 39.737 °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 132.246.11.227

peer offset 132.246.11.227 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 132.246.11.227 1.432 1.794 1.831 1.980 6.750 6.799 12.344 4.919 5.005 1.979 3.006 ms 3.072 7.55

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 142.3.100.2

peer offset 142.3.100.2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 142.3.100.2 -67.350 -54.087 -39.282 1.002 44.464 65.104 91.979 83.746 119.191 25.692 1.633 µs -3.442 8.25

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::199 (ntp2.wiktel.com)

peer offset 2600:2600::199 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2600:2600::199 (ntp2.wiktel.com) 50.982 331.487 343.501 372.433 402.785 415.577 436.232 59.284 84.090 22.687 372.355 µs 3702 5.761e+04

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:fde5:2a::13 (ntp3.torix.ca)

peer offset 2602:fde5:2a::13 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2602:fde5:2a::13 (ntp3.torix.ca) 0.249 1.460 1.471 1.502 2.082 2.095 2.121 0.611 0.634 0.255 1.643 ms 178 1074

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) -276.332 -128.736 -60.427 102.611 274.783 394.468 542.647 335.210 523.204 103.798 104.097 µs 0.3097 3.916

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::123:1 (ntp1.doit.wisc.edu)

peer offset 2607:f388::123:1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2607:f388::123:1 (ntp1.doit.wisc.edu) -0.508 -0.433 -0.341 0.981 4.646 7.192 15.780 4.987 7.626 1.697 1.410 ms 1.404 8.343

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 PPS(0)

peer offset PPS(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset PPS(0) -45.744 -23.298 -17.700 -3.159 28.242 39.619 72.404 45.942 62.917 13.953 -0.001 µs -3.053 6.984

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 132.246.11.227

peer jitter 132.246.11.227 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 132.246.11.227 0.000 0.041 0.070 0.416 3.126 5.336 85.479 3.056 5.295 3.301 0.996 ms 14.56 321.6

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 142.3.100.2

peer jitter 142.3.100.2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 142.3.100.2 0.010 0.015 0.021 0.041 0.094 0.785 138.971 0.073 0.770 4.850 0.264 ms 22.89 632.1

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::199 (ntp2.wiktel.com)

peer jitter 2600:2600::199 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2600:2600::199 (ntp2.wiktel.com) 4.638 7.491 9.942 19.781 41.224 57.422 3,619.747 31.282 49.931 84.912 24.885 µs 35.82 1479

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:fde5:2a::13 (ntp3.torix.ca)

peer jitter 2602:fde5:2a::13 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2602:fde5:2a::13 (ntp3.torix.ca) 4.079 7.954 11.469 363.505 579.920 595.660 1,676.006 568.451 587.706 239.817 276.200 µs 0.5256 1.834

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) 6.452 12.240 16.792 40.500 168.502 286.014 545.354 151.710 273.774 53.911 59.308 µs 3.2 16.73

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::123:1 (ntp1.doit.wisc.edu)

peer jitter 2607:f388::123:1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2607:f388::123:1 (ntp1.doit.wisc.edu) 2.149 4.148 6.176 12.675 23.678 31.458 45.148 17.501 27.310 5.627 13.646 ms 8.162 26.61

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 PPS(0)

peer jitter PPS(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter PPS(0) 1.569 5.216 7.480 17.036 34.445 44.522 73.795 26.965 39.306 8.401 18.432 µs 6.389 20.76

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 78.368 78.425 78.466 78.654 78.723 78.766 78.831 0.257 0.341 0.078 78.629 ppm 1.019e+09 1.026e+12
Local Clock Time Offset -45.743 -23.297 -17.699 -3.158 28.241 39.618 72.403 45.940 62.915 13.952 -0.001 µs -3.052 6.984
Local RMS Frequency Jitter 2.284 3.513 4.220 6.557 9.261 10.593 16.714 5.041 7.080 1.568 6.630 ppb 43.76 180.4
Local RMS Time Jitter 5.323 9.285 11.399 18.267 26.708 30.435 42.978 15.309 21.150 4.684 18.550 µs 35.19 136.6
Server Jitter 132.246.11.227 0.000 0.041 0.070 0.416 3.126 5.336 85.479 3.056 5.295 3.301 0.996 ms 14.56 321.6
Server Jitter 142.3.100.2 0.010 0.015 0.021 0.041 0.094 0.785 138.971 0.073 0.770 4.850 0.264 ms 22.89 632.1
Server Jitter 2600:2600::199 (ntp2.wiktel.com) 4.638 7.491 9.942 19.781 41.224 57.422 3,619.747 31.282 49.931 84.912 24.885 µs 35.82 1479
Server Jitter 2602:fde5:2a::13 (ntp3.torix.ca) 4.079 7.954 11.469 363.505 579.920 595.660 1,676.006 568.451 587.706 239.817 276.200 µs 0.5256 1.834
Server Jitter 2606:4700:f1::1 (time.cloudflare.com) 6.452 12.240 16.792 40.500 168.502 286.014 545.354 151.710 273.774 53.911 59.308 µs 3.2 16.73
Server Jitter 2607:f388::123:1 (ntp1.doit.wisc.edu) 2.149 4.148 6.176 12.675 23.678 31.458 45.148 17.501 27.310 5.627 13.646 ms 8.162 26.61
Server Jitter PPS(0) 1.569 5.216 7.480 17.036 34.445 44.522 73.795 26.965 39.306 8.401 18.432 µs 6.389 20.76
Server Offset 132.246.11.227 1.432 1.794 1.831 1.980 6.750 6.799 12.344 4.919 5.005 1.979 3.006 ms 3.072 7.55
Server Offset 142.3.100.2 -67.350 -54.087 -39.282 1.002 44.464 65.104 91.979 83.746 119.191 25.692 1.633 µs -3.442 8.25
Server Offset 2600:2600::199 (ntp2.wiktel.com) 50.982 331.487 343.501 372.433 402.785 415.577 436.232 59.284 84.090 22.687 372.355 µs 3702 5.761e+04
Server Offset 2602:fde5:2a::13 (ntp3.torix.ca) 0.249 1.460 1.471 1.502 2.082 2.095 2.121 0.611 0.634 0.255 1.643 ms 178 1074
Server Offset 2606:4700:f1::1 (time.cloudflare.com) -276.332 -128.736 -60.427 102.611 274.783 394.468 542.647 335.210 523.204 103.798 104.097 µs 0.3097 3.916
Server Offset 2607:f388::123:1 (ntp1.doit.wisc.edu) -0.508 -0.433 -0.341 0.981 4.646 7.192 15.780 4.987 7.626 1.697 1.410 ms 1.404 8.343
Server Offset PPS(0) -45.744 -23.298 -17.700 -3.159 28.242 39.619 72.404 45.942 62.917 13.953 -0.001 µs -3.053 6.984
Temp LM0 37.000 37.000 38.000 40.000 41.000 41.000 42.000 3.000 4.000 0.869 39.641 °C
Temp LM1 34.000 34.000 35.000 36.000 38.000 39.000 39.000 3.000 5.000 0.950 36.450 °C
Temp LM10 32.000 33.000 33.000 35.000 37.000 38.000 39.000 4.000 5.000 1.139 34.903 °C
Temp LM2 32.000 33.000 33.000 35.000 36.000 36.000 37.000 3.000 3.000 0.879 34.601 °C
Temp LM3 37.000 37.000 38.000 40.000 41.000 41.000 42.000 3.000 4.000 0.872 39.638 °C
Temp LM4 35.000 35.000 35.000 36.000 38.000 39.000 40.000 3.000 4.000 0.829 36.571 °C
Temp LM5 61.000 62.000 62.000 63.000 64.000 64.000 64.000 2.000 2.000 0.571 63.072 °C
Temp LM6 39.000 40.000 40.000 42.000 43.000 44.000 44.000 3.000 4.000 0.935 41.652 °C
Temp LM7 37.000 38.000 39.000 40.000 42.000 43.000 44.000 3.000 5.000 1.039 40.232 °C
Temp LM8 38.000 39.000 40.000 41.000 42.000 43.000 44.000 2.000 4.000 0.963 40.947 °C
Temp LM9 36.000 37.000 38.000 39.000 41.000 42.000 43.000 3.000 5.000 1.088 39.487 °C
Temp ZONE0 39.000 40.000 40.000 42.000 43.000 44.000 45.000 3.000 4.000 0.964 41.763 °C
Temp ZONE1 37.000 38.000 38.000 40.000 41.000 42.000 42.000 3.000 4.000 0.938 39.737 °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.
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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