tailieunhanh - Statistical Process Control 5 Part 3

Tham khảo tài liệu 'statistical process control 5 part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Process data collection and presentation 57 applications are limited to the presentation of proportions since the whole pie is normally filled. The use of graphs All graphs except the pie chart are composed of a horizontal and a vertical axis. The scale for both of these must be chosen with some care if the resultant picture is not to mislead the reader. Large and rapid variations can be made to look almost like a straight line by the choice of scale. Similarly relatively small changes can be accentuated. In the pie chart of Figure the total elimination of the defect D will make all the others look more important and it may not be immediately obvious that the pie will then be smaller. The inappropriate use of pictorial graphs can induce the reader to leap to the wrong conclusion. Whatever the type of graph it must be used with care so that the presentation has not been chosen to prove a point which is not supported by the data. Conclusions This chapter has been concerned with the collection of process data and their presentation. In practice process improvement often can be advanced by the correct presentation of data. In numerous cases over many years the author has found that recording performance and presenting it appropriately is often the first step towards an increased understanding of process behaviour by the people involved. The public display of the voice of the process can result in renewed efforts being made by the operators of the processes. Chapter highlights Process improvement requires a systematic approach which includes an appropriate design resources materials people process and operating instructions. Narrow quality and process improvement activities to a series of tasks of a manageable size. The basic rules of the systematic approach are no process without data collection no data collection without analysis no analysis without decision no decision without action which may include no action . Without records analysis is not possible. .