SLAC logo Round trip delay distributions between SLAC & CERN
Les Cottrell, Warren Matthews and Connie Logg, Last Update: December 24, 1998
Central Computer Access | Computer Networking | Internet Monitoring | ICFA-NTF Monitoring
SLAC Welcome
Highlighted Home
Detailed Home
The chart below shows a snap-shot of the frequency distribution of the round trip delay between SLAC and CERN measured in December 1998. Also shown are some statistics for the distribution.
frequency histogram of SLAC<=>CERN round trip

The next chart shows a Pareto distribution of the same data together with a power series fit with shape parameter 1.0081. For more on the Pareto distrbution see An Introduction to Probability Theory and its Applications, William Feller, volume II, Wiley Esatern Ltd., 1988 and Statistical Process Control, John S. Oakland, 1996, Butterworth and Heinemann. This fit has an R2 which indicates a good fit. A shape parameter <= 2 means that the distribution has an infinite variance, indicating immense variability. Pareto distributions for activity and inactivity periods play key roles in models of self-similarity (see W. Willinger, V. Paxson and M. Taqqu, Self-Similarity and Heavy Tails: Structural Modeling of Network Traffic in A Practical Guide to Heavy tails: Statistical Techniques for Analyzing Heavy tailed Distributions, to be published by Birkhauser, 1997.)
Pareto histogram of SLAC<=>CERN round trip

[ Feedback | Reporting Problems ]
Les Cottrell