Quality tools

Editor's Notes

• #2: Quote taken from http://wit.ksc.nasa.gov/spc/7_tools.cfm
• #4: “Democratizing Statistics” refers to the will of Ishikawa to spread Quality control throughout the workplace. The desire to make Quality control comprehendible for all of the workers.
• #5: Also known as Ishikawa Diagrams and Cause and Effect Diagrams. By mapping out a company’s problem, new thoughts and ideas can arise to better the situation. Sheds light on situations. Diagrams begin with the problem to be solved in a rectangle.
• #6: For the example Diagram, inventory shrinkage was used. This is a measure of the shoplifted, stolen, or broken goods at a store. This is placed in a rectangle at the “head” of the fish.
• #7: Here “employees” and “shoplifters” were used as categories that problems may have come from. In other examples, it is acceptable to use Machines, Materials, Methods, and People as general categories(These are from Foster, see bibliography). These should encompass all aspects of the business.
• #8: The brainstorming process should continue until every angle is covered. Keeping asking for examples until no more exist. According to Foster, 5 causes should be enough for most categories.
• #9: With the completion of the diagram, several points have been made about inventory shrinkage’s possible sources. These may or may not have been obvious to management before this brainstorming process occurred.
• #10: At this time, you can go back to the previous slide and brainstorm with the class about solutions to these problems, or other causes. This is the utility of the Cause-and-Effect Diagram. Moving expensive merchandise behind the counters and educating employees to their perks may be some solutions to this problem.
• #11: Histograms are used to show the different frequencies in a process. It is useful for identifying trends and relationships that can lead to quality improvements.
• #14: These numbers represent the customers order at the order window at the pizza store. For example, the first customer didn’t order any pizza, the second ordered 2 slices, the third ordered 1 and so on. It should be noticed that the highest order was 7 slices and the lowest was 0. This is used to find the range which is used to find the column width for the histogram.
• #15: With this information computed, all that is left to do is chart the histogram.
• #16: Helpful in showing orders frequencies and variation.
• #17: Most common types of orders placed is valuable information. Knowing that the average customer will order 2 slices of pizza can be implemented into Acme’s strategic plan. By taking at least 2 slices up to the window at peak hours, this can improve Acme’s customer service and speed. It makes the line move much faster making the perceived quality higher for the customer.
• #18: Vilfredo Pareto (1848-1923) originated the 80/20 Rule, which states that 80% of the problems comes from only 20% of the causes. Pareto Analysis is very similar to Histograms but it incorporates this theory into it. Pareto Analysis adds weight to the most frequently occurring things.
• #19: The % column represents the slices percentage of total frequency. This dictates the order of the Pareto diagram which is always scaled according to size.
• #20: This sheds light on the most frequently ordered quantities. It is also common to plot percentages on the same graph.
• #21: Answer #1: The Pareto Analysis Shows percentages. Is ordered to reflect frequency of occurrences. Answer #2: Helps identify trends. Useful for quality improvements and planning processes.
• #22: The rectangle, diamond and line are the standard symbols for flowcharts. There can be extra/different symbols depending on the process/business. The important thing is that it is consistent and maps out the process efficiently. Once flowcharts are effectively drawn they can shed light on possible problems or improvements.
• #24: Acme’s flowchart
• #25: Answer: Since we know that 2 slices is the most common order we could possibly add a step between Time to close and take customer order. If we brought two slices up to the window during peak hours this would quicken service. There are multiple improvements that can be made on the process. The class can brainstorm on ways of improving this flowchart. Note that a decision must be made at each triangle before the next step can begin.
• #27: Scatter plots take place on an X and Y graph. Whichever variable is on the bottom should be the dependent variable. This means that the Y variable changes according to changes in X. In the upcoming example, Minutes cooking the pizza’s will directly affect the number of defective pies that are produced. Scatter plots are useful for finding direct or indirect relationships which can then be used to analyze/improve quality.
• #28: This is meant to show the data. It isn’t too difficult for students to see that there is a direct relationship between Minutes cooking and defects. But the Scatter Plot will make this easier to see.
• #29: There is a direct relationship between time spent cooking by employees and defects. As Time cooking increases, so does the amount of defects.
• #30: Answer: There is obviously some kind of process problem with the number of defective pies being produced. Maybe the cooks are getting sloppy from working too fast. Or maybe morale is low and there is just apathetic work being done. Whatever the case, if this was actually happening, quality improvements would have to be studied and implemented.
• #31: Run Charts are used to plot data based on time. It’s very useful for identifying trends and cycles. The X-axis is usually the time element and the y axis is the process to be tracked. The following slide shows another Acme example that should make this easy to understand.
• #32: Ask the class what trends they can identify. Week 2’s Thursday was a rainy day. Business Peaks between 1 and 3 each night so this is very valuable information to the management. Also with the exception of the rainy day, business seems to increase with warmer weather. Have the class come up with any other trends they can see or ideas to help improve quality based on this information. Such as higher staffing between 1 and 3 or higher inventory levels/preparation etc.
• #33: Control charts are a means of regulating a process. It tracks the output of a process and its conformance to the company’s standards. As long as the process stays within the upper and lower limits then the process is “safe” and normal. Any observations made outside of the limits are irregular and problematic. They need to be immediately researched to improve quality. A process that consistently stays “safe” is a good quality process.
• #34: X= mean The majority of observations have fallen close the average. The one that’s under the lower limit is irregular, it needs to be examined and fixed.
• #35: The average Diameter can be calculated by taking the average of a sample number of pizzas. As long as the sample’s average is close enough to 16 inches to satisfy management (ex. Within +/- .01 inches) then the average can be said to be 16 inches. Then from that management can decide what is the biggest/smallest allowable pies that are acceptable.
• #36: Monitoring the pizza process, this example shows how almost every pie is within specifications. The process should be analyzed to discover why the one small pie was produced and corrected to improve quality.
• #37: Once the process is fixed the Control Chart continues to flow, any further abnormalities also need to be studied and fixed.
• #38: All of these tools together can provide great process tracking and analysis that can be very helpful for quality improvements. These tools make quality improvements easier to see, implement and track.