Lot Quality Assurance Sampling
Encyclopedia
Lot quality assurance sampling (LQAS) is a simple, low-cost random sampling methodology developed in the 1920s to control the quality
of output in industrial production processes.
LQAS involves taking a small random sample
(a 'lot') and then testing a sample of this lot for quality or the desired characteristic.
It is often stated that 19 'lots' is generally a good number, although the justification for this is unclear. One possibility is that a sample size of 19 provides an acceptable level of error for making management decisions; at least 92% of the time, it identifies whether a coverage benchmark has been reached or whether a lot is substantially below standard. Given this, samples larger than 19 would have practically the same statistical precision as 19. Thus, they would not result in better information, but would cost more to measure.
Quality control
Quality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects:...
of output in industrial production processes.
LQAS involves taking a small random sample
Random sample
In statistics, a sample is a subject chosen from a population for investigation; a random sample is one chosen by a method involving an unpredictable component...
(a 'lot') and then testing a sample of this lot for quality or the desired characteristic.
It is often stated that 19 'lots' is generally a good number, although the justification for this is unclear. One possibility is that a sample size of 19 provides an acceptable level of error for making management decisions; at least 92% of the time, it identifies whether a coverage benchmark has been reached or whether a lot is substantially below standard. Given this, samples larger than 19 would have practically the same statistical precision as 19. Thus, they would not result in better information, but would cost more to measure.