As quoted on LeCroy's web site as of Spring 1999. Timing failures are caused by worst case rather than typical events. It is the standard deviation because the figures are all RMS figures. We will now put these figures into perspective and illustrate the impact an end-user should anticipate as a result of employing a less repeatable solution. The first step is to convert from RMS to worst-case.
Timing is strictly about worst-case events.
To measure jitter effectively, it is necessary that measurement error be appropriately less than the jitter you're trying to measure. For example, if you're trying to measure 50 psec jitter, your tool shouldn't add any more than 10 psec jitter, and you're better off with less. While wearing our consultant's hat, we haven't been involved with any clock activities where multi-hundred picosecond jitters were present since the early 90's. Before departing the subject of repeatability, we need to address a further point where a user can become easily confused. This is what we have put into the first table above.