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Questions about charting attribute data in Minitab

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Viewing 5 posts - 1 through 5 (of 5 total)
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  • #37558

    Jamie
    Participant

    Hey all.  I am working on a Greenbelt project with 2 Ys.  y1 is Negative Unproductive Time incurred by Field Technicians in a dispatching oriented service industry (in hours) which is variable/continuous data.  y2 is invoicing accuracy which is attribute data and is defective as right now defects per invoice are unknown ( I am in the Measure phase). 
    Anyway, I was able to get the population of all invoices from Jan 1 to Oct8 and use that as my population.  Of the 12,449 invoices, 802 of them had 0% gross margin or even less.  For my study I am using the 802 invoices that incurred no profit as my defects.  I already determinend the yield (93.56%), defects (6.44%), DPMO (64,423) and Sigma level (3.02). 
    My question is what is the best way to put this data into minitab so I can chart process compatibility, control charts, etc.  I have totals and the raw data and have tried a few things but I cannot even get a simple histagram to form.  Any help is appreciated :)
     

    0
    #111131

    Bryant
    Participant

    In excel-1 column for a 1, 2, 3, 4, etc… count of all of the invoices.  1 column for the opportunities for error on each invoice (I couldn’t tell from your posting if the invoice was “pass/fail” or degrees of wrong).  1 column for the number of defects per invoice.
    Opportunity for multiple defects per invoice

    Invoices
    Defective (No profit)?
    Opportunities for Defects
    Defectcs

    1
    Yes
    3
    2

    2
    No
    3
    0

    3
    No
    3
    0

    4
    No
    3
    0

    5
    No
    3
    0

    6
    Yes
    3
    1
    Invoice is either pass or fail (period):

    Invoices
    Defective (No Profit)?

    1
    Yes

    2
    No

    3
    No

    4
    No

    5
    No

    6
    Yes
    Keep in mind that the continuous tools in Minitab often do not work on discrete data.  Binary Logistic Regression is a good tool to look at discrete data with (similar to General Linear Model for Continuous Data).
    Hope this helps.
    Christy

    0
    #111132

    Bryant
    Participant

    In excel-1 column for a 1, 2, 3, 4, etc… count of all of the invoices.  1 column for the opportunities for error on each invoice (I couldn’t tell from your posting if the invoice was “pass/fail” or degrees of wrong).  1 column for the number of defects per invoice.
    Opportunity for multiple defects per invoice

    Invoices
    Defective (No profit)?
    Opportunities for Defects
    Defectcs

    1
    Yes
    3
    2

    2
    No
    3
    0

    3
    No
    3
    0

    4
    No
    3
    0

    5
    No
    3
    0

    6
    Yes
    3
    1
    Invoice is either pass or fail (period):

    Invoices
    Defective (No Profit)?

    1
    Yes

    2
    No

    3
    No

    4
    No

    5
    No

    6
    Yes
    Keep in mind that the continuous tools in Minitab often do not work on discrete data.  Binary Logistic Regression is a good tool to look at discrete data with (similar to General Linear Model for Continuous Data).
    Hope this helps.
    Christy

    0
    #111467

    melvin
    Participant

    Jamie
    Consider creating a control chart in Minitab.
    It sounds like you know the number of defective invoices by month.  You just need to decide on the appropriate control chart. 
    Answer the following questions:
    1.  Do you know number of good and bad?  If no – use I chart.
    2.  If yes, do you have constant sample size? 
              If yes – use np chart
              If no – use p chart
     
    This will give you some understanding of the baseline process performance & whether special or common cause issues should be initial focus for improvement.
    Regards,
    Bob 

    0
    #111500

    Gutierrez
    Participant

    In Minitab14, there is Analysis of Means under Stat, ANOVA.  You can do Poisson and binomial charting there.  The graph may or may not be useful to you depending on what you are looking for.

    0
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