Accuracy is not the same as Precision


    It took me a little while to wrap my brain around this concept and it is a very important
    one, especially when it comes to outsourcing or any Lean Six Sigma effort.

    Shigeo Shingo makes this distinction very well with a good example.

    If say you want to divide $1000 among three people with a tolerance of $10 or less (Note that this our definition of how accurate we want to be).

    One way to make this division is:

    A: $330
    B: $330
    c: $340

    According to our definitions it is Accurate but may not be very Precise.

    Another way to do this is:

    A: $333
    B: $333
    C: $334

    This is still accurate but more Precise.

    You could go further and divide it this way:

    A: $333.33
    B: $333.33
    C: $333.34

    This is still Accurate and even more Precise!

    The idea here is depending upon what your definition of Accuracy is, more Precision
    may be very expensive but not that useful!

    Service Processes and application of Lean Six Sigma also can put this lesson to good
    use. Whether you are measuring Average Handle Time or Customer Satisfaction, more precision
    may be very expensive compared to the accuracy it adds!

    Let’s say a customer satisfaction survey comes back with a score of 1.4 on a scale of 1 to 5 (1 – Very Dissatisfied, 5 – Very Satisfied). Does a score of 1.4 matter very much from 1.39 or 1.445? The customer is gone and not coming back, anyway.

    Something to think about!

    It is the mark of an educated mind to rest satisfied with the degree of precision
    which the nature of the subject admits and not to seek exactness where only an
    approximation is possible.

    — Aristotle


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