Manag., January-2017-Q29
- Option : B
- Explanation : The American Society for Quality Control defines quality as “the totality of features and characteristics of a product and services that bears on its ability to satisfy given needs.” Quality control exercises can be carried out in two ways: after-process control and inprocess control. In after-process control, the specific features of the products are measured and compared with the pre-established specifications of the product. In-process control techniques measure the product attributes at various intervals during the manufacturing process in order to identify deviations from the established norms. Statistical quality control can be used for both process control and product control. Several techniques of in-process control such as flow chart, Pareto analysis, cause and effect (fishbone diagram), and control charts are available.
Control charts can be broadly classified into two categories. These are: (1) control charts for variables and (2) control charts for attributes. x chart and R chart can be placed in the first category and c chart, p chart and np chart can be placed in the second category. x chart is the chart of averages constructed using sample means for a series of small random samples, over a period of time whereas R chart is a plot of sample ranges. p charts graph the percentage (proportion) of defectives per sample whereas c chart graphs the number of defectives per item or unit, np chart is used to control the actual number of defective items in a sample when the sample size is constant.
In some cases, statistical process control is neither viable nor desirable. In these cases, acceptance sampling is used for quality control check. In acceptance sampling, a sample is selected from a lot or batch. On the basis of the information obtained from thesample, a lot or batch is accepted or rejected. In general, acceptance sampling plans can be broadly classified into three categories: single-sample plan, double-sample plan, and multiple-sample plan.
