Quality controla process that evaluates output relative to a standard and takes corrective action when output doesn't meet standardsinspection<span>appraisal of goods and services -necessary to physically examine some of the goods</span>acceptance samplingDo existing shipments meet predetermined standards?process controlIs the process stable? Future Output Acceptable?inspection<span>How Much to Inspect/How Often At What points should inspection occur Centralized vs. On-site Attributes vs. Variables</span>where to inspect in the process<span>Raw materials and purchased parts Finished products Before a costly operation Before an irreversible process Before a covering process</span>centralized labspecial equipment, more favorable testing atmosphere, etcon sitequicker decisions, avoidance of other extraneous factors,etc.attributes<span>characteristics which are present or not present; they are counted EX: is the top of the bottle cracked or not?</span>variables<span>characteristics which are present in varying degrees; they are measured EX: diameter of a washer bolt</span>acceptance samplingForm of inspection applied to lots or batches of items before or after a process, to judge conformance with predetermined standardssampling plansPlans that specify lot size, sample size, number of samples, and acceptance/rejection criteriasingle plan<span>one random sample is drawn from the lot and every item in sample is examined. < c defects; Accept > c defects; Reject</span>double plan<span>take a second sample if first is inconclusive. < c1 defects; Accept > c2 defects; Reject in second sample: < c3 defects; Accept > c3 defects; Reject</span>multiple plan<span>same logic as double-plan except additional samples are drawn until you clearly fall into either the acceptance or rejection category -Choosing a plan depends on cost and time. cost of analysis vs. cost of drawing sample</span>operating characteristics curve<span>It is generally not optimal to inspect all items so we have to sample some %. The problem is that you can't discriminate perfectly between good and bad lots without 100% inspection. -An important feature is how well it discriminates between lots of high quality and lots of low quality. -shows the probability that use of the sampling plan will result in lots with various fraction defectives being accepted</span>acceptance quality level (AQL)the percentage level of defects at which consumers are willing to accept lots as "good" (1-2%)lot tolerance percent defective (LTPD)the upper limit on the percentage of defects that a consumer is willing to acceptconsumers risk (beta)the probability that a lot containing defectives exceeding the LTPD will be accepted
