Bad Actor Analysis

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Introduction3/11/2017Ronald Morgan Shewchuk1Sometimes our process goes awry and the root cause is blatantly obvious.Since the root cause is established, countermeasures can be implemented to prevent recurrence of the out of control process condition. Other times the root cause is not apparent and investigations must be conducted to drill down to the root cause(s). One-way ANOVA (Analysis of Variance) is a useful tool for identifying the Bad Actor in your process.The ANOVA technique was invented by Sir Ronald Aylmer Fisher, a British mathematician, in the 1920s.ANOVA conducts tests of hypotheses to determine if the means of three or more populations are different.If we were only comparing two populations of data we would choose a 2-Sample t -Test to analyze the data.Let us visit Niels Kohr in Case Study XXI to see a practical application of one-way ANOVA for Bad Actor Analysis.

Operational Excellence


Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk2Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingBackground

Niels Kohr, process engineer at a local aluminum extrusion company, was putting the finishing touches on his mental agenda for the day during his morning commute to work. As he opened the front door to his manufacturing building, the carefully planned agenda vaporized. Todd Larssen, the General Manager of the company, was waiting for him.Niels, we have a problem in the coating area. All the coating lines are down due to peel strength failure! Can you help us?

Neils dropped off his lunch box, grabbed his hard hat, safety glasses and coveralls and headed out to the coating area. Indeed, all ten coating lines were down. He interviewed the coating area Supervisor and Operators to get their assessment of the chain of events that had led to the shutdown. Neils inspected the equipment on each coating line for any abnormality which would cause peel strength failure. He scrolled back through the Human Machine Interfaces (HMI) for each controller to search for process upset conditions. After several hours, he was unable to find an assignable cause for the low peel strengths.

Niels returned to his office and downloaded the process equipment operating data from the Data Historian on the server and the associated QC test data from the Laboratory Information Management System (LIMS) for the last four days. His analysis steps and rationalizations are captured in the following slides.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk3Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion Coating

Download process equipment operating data from Data Historian and the associated QC test data from the Laboratory Information Management System (LIMS) for the last four days to Excel.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk4Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingCopy and paste the data from Excel to a new worksheet in Minitab.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk5Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingStep 1: Look at the Big Picture. Generate Individuals SPC Chart for Peel Strength for all Coating Lines. Click on Stat Control Charts Variables Charts for Individuals Individuals on the top menu.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk6Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingSelect C14 Peel Strength (gm force) as Variables in the dialogue box. Click Scale.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk7Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingClick the toggle button for Stamp. Double Click C2 Time. Then Double Click C1 Date. Click Gridlines tab.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk8Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingCheck the box for Y major ticks. Click OK. Then click OK one more time.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk9Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingThe Individuals SPC Chart is generated for Peel Strength. Outliers are highlighted with red squares.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk10Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingClick the brush icon on the top menu. Left click and drag the box to highlight the low outliers. Lets see what is driving these outliers.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk11Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingReturn to the active worksheet. Scroll down until the brushed columns appear. These will have black dots next to the row numbers. There is nothing here that immediately catches Niels attention. He elects to perform One-way ANOVA analysis on the data by Coating Line.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk12Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingClick Assistant Hypothesis Tests on the top menu.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk13Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingSince we have ten coating lines. Click Help Me Choose under Compare more than two samples.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk14Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingThe Peel Strength data is continuous and Niels wants to compare the means of the coating lines. Click One-Way ANOVA.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk15Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingSelect Y data are in one column, X values in another column for data arrangement in the worksheet. Select C14 Peel Strength (gm force) for Y data column and C3 Line No. for X values column. Leave the significance level, Alpha at 0.05. Click OK.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk16Four reports are generated by the One-Way ANOVA analysis. This is the Summary Report which indicates that there are no differences between the Peel Strength means by coating line.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk17This is the Diagnostic Report which indicates that the majority of coating lines have peel strength outliers.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk18This is the Power Report which indicates individual statistics by coating line and the ability to detect mean differences.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk19This is the Report Card which indicates warnings and information about unusual data points, sample size, normality and individual population variances.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk20Niels has not found the smoking gun. He returns to the active worksheet. Niels rationalizes that since coating lines are not assigned to any specific tensile tester, there should be no peel strength differences between peel strength test instruments. He proceeds to check.

Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion Coating



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk21Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion Coating

Click Assistant Hypothesis Tests on the top menu.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk22Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingClick One-Way ANOVA in the dialogue box.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk23Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingReplace Line No. with Tensile Tester No. in the X values column. Click OK.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk24Tensile Tester No. 292 is indicated as a Bad Actor in the Summary Report. It has significantly lower mean peel strength vs the other Tensile Test Instruments.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk25Tensile Tester No. 292 has had a mean shift down in measured peel strength.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk26Niels brushes the point at the beginning of the mean shift and finds the corresponding worksheet row to be 122.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk27The black dot at row number 122 indicates that the problem with Tensile Tester No. 292 started on Feb 17 at 01:33. This allows Niels to define the scope of the nonconformity.

Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion Coating



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk28

The Power Report indicates not only a low mean but also a high standard deviation due to the mean shift in Peel Strength for Tensile Tester No. 292.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk29The Report Card indicates no warnings. Niels can be confident in his conclusions about Tensile Tester No. 292.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk30Click on the Show Graphs Icon on the top menu. Highlight all graphs. Right click over the highlighted graphs and select Send to Microsoft PowerPoint. This produces a slide show presentation which will allow Niels to share with the production team.



Bad Actor Analysis3/11/2017Ronald Morgan Shewchuk31Case Study XXI: One-Way ANOVA Analysis of Aluminum Extrusion CoatingSummary

Niels presented his findings to the production team including the QC Manager, Elsa Anderssen. Elsa offered to begin daily SPC monitoring of the tensile testing instruments using calibrated weights on the load cells. She also agreed to modify the Response Flow Checklist for Non-conforming Material to validate peel strength results with another Tensile Tester before declaring the production sample as discrepant.

There were high-fives all around the table and the production group was delighted to get back into business. As the group filed out of the conference room Todd Larssen slapped Neils on the back and said,That was some fine detective work Neils! How about we go out to celebrate with a beer?It had been a long day. Neils paused for a moment and then responded,I think I would rather go out for ice cream



Bad Actor Analysis

Bad Actor Analysis

Engineering

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