Basic Tools for Process Improvement

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Basic Tools for Process Improvement Portraying your data in a Histogram enables you to check rapidly on the number, or the percentage, of defects produced during the time you collected data. But unless you know whether the process was stable (Viewgraph 15), you won’t be able to predict whether future products will be within specification limits or determine a course of action to ensure that they are. A Histogram can show you whether or not your process is producing products or services that are within specification limits. To discover whether the process is stable, and to predict whether it can continue to produce within spec limits, you need to use a Control Chart (see the Control Chart module). Only after you have discovered whether your process is in or out of control can you determine an appropriate course of action—to eliminate special causes of variation, or to make fundamental changes to your process. There are times when a Histogram may look unusual to you. It might have more than one peak, be discontinued, or be skewed, with one tail longer than the other, as shown in Viewgraph 16. In these circumstances, the people involved in the process should ask themselves whether it really is unusual. The Histogram may not be symmetrical, but you may find out that it should look the way it does. On the other hand, the shape may show you that something is wrong, that data from several sources were mixed, for example, or different measurement devices were used, or operational definitions weren't applied. What is really important here is to avoid jumping to conclusions without properly examining the alternatives. 18 HISTOGRAM
Target Interpreting Histograms Process Variation Day 1 Target Day 2 Day 3 Day 4 Target Target HISTOGRAM VIEWGRAPH 15 Skewed (not symmetrical) Basic Tools for Process Improvement Interpreting Histograms Common Histogram Shapes Discontinued Symmetrical (mirror imaged) HISTOGRAM VIEWGRAPH 16 HISTOGRAM 19
Page 1 and 2: Basic Tools for Process Improvement
Page 3 and 4: 100 80 60 40 20 0 Basic Tools for P
Page 5 and 6: 4 5 F R E Q U E N C Y 100 80 60 40
Page 9 and 10: How to Construct a Histogram Step 1
Page 13 and 14: Interval Width Step 5 - Compute the
Page 15 and 16: S H O T C O U N T LEGEND: 25 20 15
Page 17: Interpreting Histograms Location an
Page 23 and 24: Interval Width Basic Tools for Proc
Page 25 and 26: EXERCISE 1 ANSWER KEY Step 1 - Coun
Page 27 and 28: Interval Width Basic Tools for Proc
Page 33 and 34: NO. OF PERSONNEL 30 25 20 15 10 5 0
Page 35 and 36: HISTOGRAM VIEWGRAPH 1 • A bar gra
Page 37 and 38: HISTOGRAM VIEWGRAPH 3 5 1 Title 2 H
Page 39 and 40: HISTOGRAM VIEWGRAPH 5 Step 9 - Add
Page 41 and 42: HISTOGRAM VIEWGRAPH 7 410 1 - 180 1
Page 43 and 44: HISTOGRAM VIEWGRAPH 9 More than 250
Page 45 and 46: HISTOGRAM VIEWGRAPH 11 Equal to or
Page 47 and 48: HISTOGRAM VIEWGRAPH 13 Target Targe
Page 49 and 50: HISTOGRAM VIEWGRAPH 15 Target Targe
Page 51 and 52: HISTOGRAM VIEWGRAPH 17 TOTAL NUMBER
Page 53 and 54: HISTOGRAM VIEWGRAPH 19 Range of val
Page 55 and 56: HISTOGRAM VIEWGRAPH 21 Round up to
Page 57 and 58: HISTOGRAM VIEWGRAPH 23 Step 8 - Plo
Page 59 and 60: HISTOGRAM VIEWGRAPH 25 % FAT NO. OF
Page 61 and 62: HISTOGRAM VIEWGRAPH 27 More than 25
Page 63 and 64: HISTOGRAM VIEWGRAPH 29 Equal to or
Page 65 and 66: HISTOGRAM VIEWGRAPH 31 TOTAL = 105
Page 67 and 68: HISTOGRAM VIEWGRAPH 33 Range of val
Page 69 and 70:
HISTOGRAM VIEWGRAPH 35 Round up to
Page 71:
HISTOGRAM VIEWGRAPH 37 LEGEND: MCBH
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Basic Tools for Process Improvement

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