One is the threshold at which a defect is created, the other is a limit that is established to prevent losing process control--thus the term "control limits
The upper control limit
is three sigmas above the mean and the lower control limit
is three sigmas below the mean.
For this purpose, the failure control limit
q to determine the failure time and the fault trend control limit
[l.sub.1] for early detection of slowly varying fault should first be determined.
In the case of a green sand system, engineers are not necessarily looking for outliers (individual test results falling outside the control limits
), but rather looking at the overall chart line to see if the system is trending upward or downward toward one of the control limits
The fluctuation of stock in the supermarket between the upper and lower control limits
can then be assessed.
His graphs show continuous temperature plots generally tracking within the control limits
and excursions (out of "control") which may indicate events--a change of energy (sunspot activity etc.
By repeating tests of the SRM bullets and cartridge cases at local and state IBIS sites, and correlating the images with the Golden Images established at the ATF, control charts and control limits
were developed for quality assurance of ballistics acquisitions and correlations in NIBIN.
It follows that if a process is given and its auto covariance can be found then, at least theoretically, [2.sigma over bar.x] , E(s) and Std(s) can be found and, therefore, the control limits
on [bar.x] and s can also be computed.
In the following, for determining the control limits
, two approaches are explained, namely, probabilistic approach and membership approach.
Repeat strategy Description Rule 1 If all initial QC results are within mean [+ or -] 2s control limits
, then accept.