9 thoughts on “Expectations of arithmetic capability in a $940 expert witness”

  1. The lawyer was exploiting a common misconception, that a skill in arithmetic correlates with intelligence and with accurate results. There is a word to describe people who do arithmetic on the fly. The word is “wrong”. When it counts, you do arithmetic on a calculator or a computer, and you have another person or a committee review your work. The expert failed to explain this well and the dramatization made him appear hesitant and upset which may not have been the case in real life.

    We teach math and arithmetic by giving students many calculations to perform and awarding them A’s if their error rate is less than 10%. Most real life problems require far fewer calculations to perform but the consequences of error rates approaching 10% are far greater. Perhaps this is responsible for the misconception.

  2. The witness’s testimony is inconsistent. He says that the distance is 3 and 3/16 inches on the diagram, and around 68 feet in the real world. Applying the 1 inch : 20 foot scale, 3 and 3/16 on the diagram would translate to about 64 feet. A distance of 68 feet would be a little more than 3 and 3/8 on the diagram. The lawyer may have noticed this, and started talking about the arithmetic in an effort to expose the inconsistency.

    I can only speculate, but I would not be surprised if the witness was able to do the arithmetic in the moment (the video says that he had a calculator, btw) and got confused when his result did not agree with the numbers he reported earlier.

  4. And you decry the quality of education provided in public schools. LOOK at the money this guy is making and he can’t do a math problem under pressure.

    There’s no need for Bernie-Sanders-free-college, that guy is billing nearly a grand with a sixth grade education.

  5. I bet the way it was enacted wasn’t how the lawyer approached the problem in real life. That’s because I assume the lawyer knew what the correct answer was, knew the expert was wrong, and so thoroughly enjoyed the entire proceedings.

    OTOH, give me a calculator and I would be worried too. Calculators suck. Either ask me to do it in my head, ask me to do it on paper, give me a spreadsheet, or access to emacs. Not sure whether I’d prefer an E6B slide rule or maybe a calculator that shows a decent history.

    When I tutor, I take away the calculators, I make the kids do (most of) the math by hand, and regardless of the actual course being taught, they all improve dramatically in understanding, speed and accuracy.

  7. @Jerry, then why didn’t this expert ask for a pen and paper to convert the number? The fact is that if you can do it by hand then doing it on a simple calculator should take less than five seconds. Even if you use the calc function in Emacs or some other way (I’m still an Emacs newb), it would still require him to understand the basic principle of ratios and how to apply them.

  8. I don’t see an issue. The lawyer is trying to trip him up. What other experts are asked to perform their respective analysis “live” either at trial or deposition?

  9. The witness originally got the calculation wrong, probably copying it incorrectly. The lawyer caught the error, as lawyers will sometimes do. I’ll bet the witness did the calculation in his head on the spot (not all that difficult, even under the stress of some merciless badgering), saw that he had screwed up and didn’t want to admit it in testimony. His “I can’t perform this calculation unassisted by a mainframe computer and a battalion of mathematicians” responses look like a tactic to avoid admitting that he’d made an error.

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