Incompetence or Nervousness?

defending your claims

In #articles

I’ve been seeing a lot of talk about the supposedly incompetent response by “accident reconstruction expert”, as shown in this video. You can read one response in the opinion piece in the NY Times. The summary is that the “expert” was supposedly unable to perform the following calculation:

For those who may be curious about the specific math, let me lay out the numbers. The diagram had a distance the witness measured as 3 and three-sixteenths inches with a scale of 20 feet per inch. The witness said this came to approximately 68 feet. In fact it is 63.75 feet. If the expert witness had taken a few seconds to use his calculator, he could have (hopefully) come to the same conclusion.

I watched the video, and can confirm that the expert should have done better, but I am not entirely convinced that this is incompetence. I could imagine someone being nervous about lawyers, feeling that the questions were going to be “gotcha” questions - or at least lead to that - and that you’d want a away to double-check any calculation. Although looking bad, imagine if he had tried this calculation and (through nervousness) came to an incorrect number. How bad would that look? Certainly that would have looked worse. What if he came to the correct number, but noticed the discrepancy - he’d still want to double-check the numbers through the methods he typically uses.

Clearly, once he had decided that the line of questioning was just trying to “get him”, whether he was competent or not, there was no way that he was going to budge.

I think his incompetence may lay in the fact that he didn’t bring the materials he needed to assess the situation quantitatively. That seems ridiculous. What sorts of lessons can we draw from this video?

  1. Always bring your materials that you need, if you’re going to be questioned about the details of a result you’ve claimed.
  2. Be prepared to address the claims on several levels of detail - from the fully quantitative level worthy of a technical report, to a back-of-the-envelope calculation which gets close to it.
  3. Listen to the question that someone is actually asking, not the question you think they are asking.

More lessons?