Application Corner: Backward problem-solving can produce uncertainty

May 17, 2018

Starting with an artifact and working the problem backward can create considerable uncertainty.

Legal work is interesting in the (twisted) sense that diametrically opposite approaches to an investigation can be taken to determine the cause of a problem. There is some art to knowing when to take which approach, but the selected approach is also dependent on the skill set of the person(s) involved. Sometimes it does not matter, but quite often the results can be strikingly different.

Confidentiality does not allow me to divulge details of actual investigations, so I will invent an example to illustrate the point. Suppose the problem is to discover what caused a round splat on a downtown sidewalk that is about 0.5 meters in diameter. The liquid part of this artifact is clear with some yellow coloring and brown/white chips throughout. Given its location, shape, color and consistency, one might speculate that the splat was made by a brown egg falling from above. Chemical testing can confirm that an egg was involved.

The roundness of the splat indicates that the egg likely fell from directly above. But which floor did it fall from? Without elaborating, different tests with different quality brown eggs can be performed to determine which quality egg dropped from which floor exhibits the same splat as the original splat. But what if the egg did not fall from a rest position but instead was thrown up or down? This question adds a certain amount of uncertainty.

The point is that starting with an artifact and working the problem backward can create considerable uncertainty. Nonetheless, working the problem backward is often the best — and sometimes the only — way to work certain problems. An example might be determining the nature of dinosaurs when you only have artifacts to study.

More next month.

David W. Spitzer is a regular contributor to Flow Control magazine and a principal in Spitzer and Boyes LLC, which offers engineering, seminars, strategic, marketing consulting, distribution consulting and expert witness services for manufacturing and automation companies. Spitzer and Boyes is also the publisher of the Industrial Automation INSIDER. He has more than 40 years of experience and has written more than 10 books and 350 articles about flow measurement, instrumentation and process control.

Spitzer may be reached at 845-623-1830 or via spitzerandboyes.com. Click on the "Products" tab to find his Consumer Guides to various flow and level measurement technologies.

About the Author

David W. Spitzer

David W Spitzer’s new book Global Warming (aka Climate Change): An Understandable Data-Driven Explanation and Pathway to Mitigation (Amazon.com) adds to his over 500 technical articles and 10 books on flow measurement, instrumentation, process control and variable speed drives. David offers consulting services and keynote speeches, writes/edits white papers, presents seminars, and provides expert witness services at Spitzer and Boyes LLC (spitzerandboyes.com or +1.845.623.1830).

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