NTPsec

crane3.services.mbix.ca

Report generated: Sun Oct 11 16:45:02 2026 UTC
Start Time: Sun Oct 4 16:45:01 2026 UTC
End Time: Sun Oct 11 16:45:01 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 -49.160 -23.667 -17.654 -3.172 28.929 41.654 72.900 46.583 65.321 14.105 -0.002 µs -2.961 6.98
Local Clock Frequency Offset 78.497 78.530 78.546 78.610 78.713 78.739 78.788 0.167 0.209 0.052 78.618 ppm 3.514e+09 5.342e+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 4.653 8.823 11.013 18.230 27.383 32.679 47.150 16.370 23.856 5.071 18.604 µs 27.55 102.7

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 1.881 3.326 4.098 6.583 9.577 11.422 17.345 5.479 8.096 1.697 6.675 ppb 34.62 136.3

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 -49.160 -23.667 -17.654 -3.172 28.929 41.654 72.900 46.583 65.321 14.105 -0.002 µs -2.961 6.98

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 78.497 78.530 78.546 78.610 78.713 78.739 78.788 0.167 0.209 0.052 78.618 ppm 3.514e+09 5.342e+12
Temp LM0 36.000 37.000 38.000 40.000 41.000 42.000 43.000 3.000 5.000 0.987 39.531 °C
Temp LM1 33.000 34.000 34.000 36.000 38.000 38.000 39.000 4.000 4.000 1.032 35.646 °C
Temp LM10 33.000 34.000 34.000 36.000 37.000 38.000 39.000 3.000 4.000 1.033 35.859 °C
Temp LM2 31.000 32.000 33.000 34.000 35.000 36.000 38.000 2.000 4.000 0.881 33.847 °C
Temp LM3 36.000 37.000 38.000 40.000 41.000 41.000 43.000 3.000 4.000 0.971 39.520 °C
Temp LM4 34.000 35.000 35.000 36.000 37.000 38.000 39.000 2.000 3.000 0.731 35.894 °C
Temp LM5 62.000 63.000 63.000 63.000 64.000 64.000 64.000 1.000 1.000 0.418 63.222 °C
Temp LM6 40.000 40.000 41.000 42.000 43.000 44.000 44.000 2.000 4.000 0.787 42.203 °C
Temp LM7 37.000 38.000 39.000 41.000 42.000 42.000 44.000 3.000 4.000 0.849 40.646 °C
Temp LM8 38.000 38.000 39.000 41.000 42.000 43.000 43.000 3.000 5.000 0.885 40.885 °C
Temp LM9 36.000 37.000 38.000 40.000 41.000 42.000 43.000 3.000 5.000 0.899 39.681 °C
Temp ZONE0 40.000 40.000 41.000 42.000 43.000 44.000 44.000 2.000 4.000 0.820 42.278 °C
Temp ZONE1 37.000 37.000 38.000 40.000 41.000 42.000 42.000 3.000 5.000 1.041 39.604 °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 132.246.11.227 562.050 621.704 666.488 748.236 835.162 861.454 928.628 168.674 239.750 51.364 748.580 µs 2542 3.506e+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 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 -71.333 -53.095 -39.727 -0.526 46.098 67.309 90.309 85.825 120.404 25.584 0.686 µs -3.554 8.59

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 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) 318.478 330.763 343.133 370.398 400.449 412.490 437.257 57.316 81.727 17.549 371.132 µs 8241 1.673e+05

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) 1.444 1.465 1.478 8.361 8.407 8.423 8.441 6.929 6.958 3.329 5.506 ms 1.942 3.065

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) -1.239 -1.037 -0.820 -0.447 -0.152 0.097 0.306 0.668 1.134 0.204 -0.458 ms -44.05 180.6

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) -7.539 -1.422 -0.518 -0.455 2.379 4.815 12.347 2.898 6.236 1.271 0.035 ms -0.3888 18.52

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) -49.161 -23.668 -17.655 -3.173 28.930 41.655 72.901 46.585 65.323 14.106 -0.002 µs -2.961 6.98

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 0.018 0.050 0.069 0.303 2.007 4.453 5.785 1.938 4.403 0.754 0.541 ms 2.521 12.83

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 0.011 0.016 0.021 0.041 0.116 1.006 239.408 0.095 0.990 13.575 1.005 ms 12.39 211.5

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) 0.004 0.007 0.010 0.020 0.041 0.064 94.505 0.031 0.057 3.646 0.246 ms 14.4 295.9

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) 0.004 0.008 0.011 0.025 0.562 0.590 6.343 0.552 0.582 0.263 0.135 ms 6.808 145.7

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) 6.175 11.995 16.341 41.710 160.881 346.046 715.520 144.540 334.051 64.399 58.724 µs 4.507 33.02

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 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) 0.005 0.010 0.013 0.033 18.368 24.817 40.160 18.354 24.807 6.892 3.922 ms 0.3794 3.741

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) 1.716 4.828 6.995 16.920 35.321 46.482 73.981 28.326 41.654 8.843 18.416 µs 5.673 18.5

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 78.497 78.530 78.546 78.610 78.713 78.739 78.788 0.167 0.209 0.052 78.618 ppm 3.514e+09 5.342e+12
Local Clock Time Offset -49.160 -23.667 -17.654 -3.172 28.929 41.654 72.900 46.583 65.321 14.105 -0.002 µs -2.961 6.98
Local RMS Frequency Jitter 1.881 3.326 4.098 6.583 9.577 11.422 17.345 5.479 8.096 1.697 6.675 ppb 34.62 136.3
Local RMS Time Jitter 4.653 8.823 11.013 18.230 27.383 32.679 47.150 16.370 23.856 5.071 18.604 µs 27.55 102.7
Server Jitter 132.246.11.227 0.018 0.050 0.069 0.303 2.007 4.453 5.785 1.938 4.403 0.754 0.541 ms 2.521 12.83
Server Jitter 142.3.100.2 0.011 0.016 0.021 0.041 0.116 1.006 239.408 0.095 0.990 13.575 1.005 ms 12.39 211.5
Server Jitter 2600:2600::199 (ntp2.wiktel.com) 0.004 0.007 0.010 0.020 0.041 0.064 94.505 0.031 0.057 3.646 0.246 ms 14.4 295.9
Server Jitter 2602:fde5:2a::13 (ntp3.torix.ca) 0.004 0.008 0.011 0.025 0.562 0.590 6.343 0.552 0.582 0.263 0.135 ms 6.808 145.7
Server Jitter 2606:4700:f1::1 (time.cloudflare.com) 6.175 11.995 16.341 41.710 160.881 346.046 715.520 144.540 334.051 64.399 58.724 µs 4.507 33.02
Server Jitter 2607:f388::123:1 (ntp1.doit.wisc.edu) 0.005 0.010 0.013 0.033 18.368 24.817 40.160 18.354 24.807 6.892 3.922 ms 0.3794 3.741
Server Jitter PPS(0) 1.716 4.828 6.995 16.920 35.321 46.482 73.981 28.326 41.654 8.843 18.416 µs 5.673 18.5
Server Offset 132.246.11.227 562.050 621.704 666.488 748.236 835.162 861.454 928.628 168.674 239.750 51.364 748.580 µs 2542 3.506e+04
Server Offset 142.3.100.2 -71.333 -53.095 -39.727 -0.526 46.098 67.309 90.309 85.825 120.404 25.584 0.686 µs -3.554 8.59
Server Offset 2600:2600::199 (ntp2.wiktel.com) 318.478 330.763 343.133 370.398 400.449 412.490 437.257 57.316 81.727 17.549 371.132 µs 8241 1.673e+05
Server Offset 2602:fde5:2a::13 (ntp3.torix.ca) 1.444 1.465 1.478 8.361 8.407 8.423 8.441 6.929 6.958 3.329 5.506 ms 1.942 3.065
Server Offset 2606:4700:f1::1 (time.cloudflare.com) -1.239 -1.037 -0.820 -0.447 -0.152 0.097 0.306 0.668 1.134 0.204 -0.458 ms -44.05 180.6
Server Offset 2607:f388::123:1 (ntp1.doit.wisc.edu) -7.539 -1.422 -0.518 -0.455 2.379 4.815 12.347 2.898 6.236 1.271 0.035 ms -0.3888 18.52
Server Offset PPS(0) -49.161 -23.668 -17.655 -3.173 28.930 41.655 72.901 46.585 65.323 14.106 -0.002 µs -2.961 6.98
Temp LM0 36.000 37.000 38.000 40.000 41.000 42.000 43.000 3.000 5.000 0.987 39.531 °C
Temp LM1 33.000 34.000 34.000 36.000 38.000 38.000 39.000 4.000 4.000 1.032 35.646 °C
Temp LM10 33.000 34.000 34.000 36.000 37.000 38.000 39.000 3.000 4.000 1.033 35.859 °C
Temp LM2 31.000 32.000 33.000 34.000 35.000 36.000 38.000 2.000 4.000 0.881 33.847 °C
Temp LM3 36.000 37.000 38.000 40.000 41.000 41.000 43.000 3.000 4.000 0.971 39.520 °C
Temp LM4 34.000 35.000 35.000 36.000 37.000 38.000 39.000 2.000 3.000 0.731 35.894 °C
Temp LM5 62.000 63.000 63.000 63.000 64.000 64.000 64.000 1.000 1.000 0.418 63.222 °C
Temp LM6 40.000 40.000 41.000 42.000 43.000 44.000 44.000 2.000 4.000 0.787 42.203 °C
Temp LM7 37.000 38.000 39.000 41.000 42.000 42.000 44.000 3.000 4.000 0.849 40.646 °C
Temp LM8 38.000 38.000 39.000 41.000 42.000 43.000 43.000 3.000 5.000 0.885 40.885 °C
Temp LM9 36.000 37.000 38.000 40.000 41.000 42.000 43.000 3.000 5.000 0.899 39.681 °C
Temp ZONE0 40.000 40.000 41.000 42.000 43.000 44.000 44.000 2.000 4.000 0.820 42.278 °C
Temp ZONE1 37.000 37.000 38.000 40.000 41.000 42.000 42.000 3.000 5.000 1.041 39.604 °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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