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Comment by Randgalt | Hacker News Reader

I side (mostly) with the expert here. I'm now in my 50s and my memory is not what it used to be. Under hostile questioning I can forget my own name sometimes. That said, you'd think an expert witness would keep his cool as he might be in a court room situation with similar questioning.

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But this isn't a memory thing. This is math with a calculator. He isn't being asked to recite the multiplication speed tables by memory. I'll admit that it can take me a couple of seconds to remember what 9 * 7 is when calculating the bill for dinner, but I can most definitely do it with a calculator, because I know that that's how math works.

I agree with what another poster has said [1]. It's likely this expert knew how to use the calculator but then saw what the answer came up as and realized, "Oh shit!". But maybe this was the "right" tactic to go with, if the expert wanted to be able to weasel his way out of a mistake (perhaps he just made a typo when he initially did the work?) without technically perjuring himself.

[1] https://news.ycombinator.com/item?id=10826365

Try doing it in a deposition or court proceeding. It's different, and anything you say is part of the court record, and any mistake, even one you correct immediately is used against you.

I've had to testify in front of a grand jury before. I definitely know that being questioned in front of people is not not as easy as typing into a discussion thread at my leisure. But again, this is not a task of recall, i.e. "what were you doing the night the victim was murdered?" or "Do you remember your mother's birthday?". This is a question of fundamentals. Again, the expert is not being asked to recall the result of `3 / 16`, he's being asked if he can do it on a calculator. This goes on for several minutes.

Here's what would be a perfectly understandable answer: "I don't recall how I got 68 when now that I calculate it, the answer appears to be 63.75" Because sure, it could be there was a typo in the initial work of the expert, and it has only now been revealed. But this is not what the expert admits to failing to. He's asked point blank if he can use a calculator: "Will you please convert 3 / 16ths to a decimal value...Can you?" And he says, "I will not do it without my reference material".

Again, completely understandable if he says "I will not do it without a calculator". That is not the issue of contention here.

I'm a bit surprised to see people jump to his defense. Calculations like these are the foundation of the science and "science" that is used to convict/fuck people over. And even though this seems to be a minor case, a difference of feet in any kind of reconstruction (scientific or witness testimony) can mean the difference between conviction and acquittal. This is just one case that has been spotted by a writer/artist to dramatize for humorous effect. There are countless more, involving less obvious mathematical errors, that may impact the justice system. That we can't even agree that this witness is either too incompetent to trust the evidence that he's provided to his side, or too disingenuous to admit his mistake...and we wonder why shit happens?

A grand jury is different -- it's secret.

Once the opposing counsel opens the door to extemporaneous testimony, you're screwed as a witness, because the next question may not be 1+1=2, it may be something else.

Right, it's not just doing tip math at dinner, it's doing tip math at dinner with everyone looking at you and the waiter tapping their feet because they want you to free up the table.

Edit: Whoops, meant this for the sibling comment.

Under stress I sometimes have trouble with calculators. I'm not kidding. It's happened to me in restaurants.

Then you shouldn't be an expert witness. My dad is in his early seventies and he can still do cubic scaling (e.g., 50m cubic cm to cubic inches) in his head without a calculator.

My mom (in her 60s) still knows where to apply compounding growth formulae, and how to estimate them.

If your memory is beginning to go on you to the point where you can no longer effectively do your job you should learn to do something which requires less memory.

Seriously? Are those even practical skills? For all we know, your parents are great at parlor tricks and terrible at their jobs. What engineer works without a computer these days?

A calculator is a computer. Hewlett Packard made calculators, which is why Steve Wozniak wanted to work there until Steve Jobs convinced him to start Apple. The expert wasn't being asked to figure out 3/16ths by memorization, he was being asked if he knew what math was, and then how to execute it on a calculator. That the expert equated such a request with pulling numbers "out of thin air" (if he's being honest, and not just covering up a mistake that he now realizes he made) means that he does not actually understand the very fundamentals of math. It is virtually no different than if he were asked, "Is 1 equal to 1?", and he responded, "I'm not just going to make up the answer for you, we need to use the computer program to get the truth"

Very few of them, but this isn't even middle school level math that he seems to be forgetting. Anyone calling themselves an engineer should know fractions cold, no question.

The man is asked to give the decimal of three sixteenths. That's not a memory quiz.

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