Maths Stuff Flashcards
Control
A measure of the predictability of a process
Capability
A measure of the ability of a process to meet customer needs
Three common terms refer to the variability of process output
Tolerances – specifications for a range of acceptable values established by engineering design or customer requirements
Control limits – statistical limits that reflect the extent to which sample statistics such as mean and ranges can vary due to randomness alone
Process variability – natural or inherent variability in a process
Improving process capability
Simplify Standardise Mistake – proof Upgrade equipment Automate
Data gathering in production can occur at three points
Before production
During production
After production
Common cause variation
Inherent in a process when it is operating as designed
Natural variations in the output of the process, created by countless minor factors
Special cause variation
Unnatural variation in a process
A variation his calls can be identified
Type I error/produces risk
Concluding a process is not in control when it actually is in control
Type II error/buyers risk
Concluding a process is in control when it is out of control
Acceptance number C
The maximum number of defective items which is acceptable in a defined sample size
Acceptable quality level AQL
The proportion defective in the batch which is the worst level the consumer is prepared to except as a process average or The proportion defective for which it is desired to accept all batches
Lot tolerance proportion defective LTPD
The poorest proportion defective the consumer will accept for any individual lot or the proportion defective for which it is desired to reject all batches
