Quality Control Tools

1. Quality Control Tools

2. Introduction The Perform Quality Control process of the Project Quality Management knowledge area has several quality control tools and techniques that are also used in the Perform Quality Assurance process. The quality control tools and techniques discussed in this article are: • Cause and Effect Diagrams • Check Sheet • Control Charts • Histogram • Pareto Chart • Scatter Diagram • Stratification By: Mark Rigor Mirondo

3. Cause and Effect Diagram Fishbone Diagram Also Called: Cause-and-Effect Diagram, Ishikawa Diagram Variations: cause enumeration diagram, process fishbone, time-delay fishbone, CEDAC (cause-and-effect diagram with the addition of cards), desired-result fishbone, reverse fishbone diagram • Description • The fishbone diagram identifies many possible causes for an effect or problem. It can be used to structure a brainstorming session. It immediately sorts ideas into useful categories. • When to Use a Fishbone Diagram • When identifying possible causes for a problem. • Especially when a team’s thinking tends to fall into ruts. By: Mark Rigor Mirondo

4. Check Sheet Check Sheet Also called: defect concentration diagram • Description • A check sheet is a structured, prepared form for collecting and analyzing data. This is a generic tool that can be adapted for a wide variety of purposes. • When to Use a Check Sheet • When data can be observed and collected repeatedly by the same person or at the same location. • When collecting data on the frequency or patterns of events, problems, defects, defect location, defect causes, etc. • When collecting data from a production process. By: Mark Rigor Mirondo

5. Control Charts Control Chart Also called: statistical process control Description The control chart is a graph used to study how a process changes over time. Data are plotted in time order. A control chart always has a central line for the average, an upper line for the upper control limit and a lower line for the lower control limit. These lines are determined from historical data. By comparing current data to these lines, you can draw conclusions about whether the process variation is consistent (in control) or is unpredictable (out of control, affected by special causes of variation). By: Mark Rigor Mirondo

6. Control Charts • When to Use a Control Chart • When controlling ongoing processes by finding and correcting problems as they occur. • When predicting the expected range of outcomes from a process. • When determining whether a process is stable (in statistical control). • When analyzing patterns of process variation from special causes (non-routine events) or common causes (built into the process). • When determining whether your quality improvement project should aim to prevent specific problems or to make fundamental changes to the process. By: Mark Rigor Mirondo

7. Histogram • Description • A frequency distribution shows how often each different value in a set of data occurs. A histogram is the most commonly used graph to show frequency distributions. It looks very much like a bar chart, but there are important differences between them. • When to Use a Histogram • When the data are numerical. • When you want to see the shape of the data’s distribution, especially when determining whether the output of a process is distributed approximately normally. Source: Nayatani, Y., The Seven New QC Tools (Tokyo, Japan, 3A Corporation, 1984) By: Mark Rigor Mirondo

8. Pareto Chart • Pareto Chart • Also called: Pareto diagram, Pareto analysis • Variations: weighted Pareto chart, comparative Pareto charts • Description • A Pareto chart is a bar graph. The lengths of the bars represent frequency or cost (time or money), and are arranged with longest bars on the left and the shortest to the right. In this way the chart visually depicts which situations are more significant. • When to Use a Pareto Chart • When analyzing data about the frequency of problems or causes in a process. • When there are many problems or causes and you want to focus on the most significant. By: Mark Rigor Mirondo

9. Scatter Diagram • Scatter Diagram • Also called: scatter plot, X–Y graph • Description • The scatter diagram graphs pairs of numerical data, with one variable on each axis, to look for a relationship between them. If the variables are correlated, the points will fall along a line or curve. The better the correlatin, the tighter the points will hug the line. • When to Use a Scatter Diagram • When you have paired numerical data. • When your dependent variable may have multiple values for each value of your independent variable. By: Mark Rigor Mirondo

10. Stratification Description Stratification is a technique used in combination with other data analysis tools. When data from a variety of sources or categories have been lumped together, the meaning of the data can be impossible to see. This technique separates the data so that patterns can be seen. When to Use Stratification Before collecting data. When data come from several sources or conditions, such as shifts, days of the week, suppliers or population groups. When data analysis may require separating different sources or conditions. By: Mark Rigor Mirondo

11. Thank You!!! Members: Mark Rigor Mirondo MhelanDasalla Almarie Fernando Roderick Galleto By: Mark Rigor Mirondo

12. ForNotListening By: Mark Rigor Mirondo