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One of the things taught in engineering school is to never trust your memory. Always work from the original formulas and reference material which has been prove

by chiph 11y ago

One of the things taught in engineering school is to never trust your memory. Always work from the original formulas and reference material which has been proven to be correct and to work.

SilasX 11y ago
You need a reference sheet to convert 3/16 to a decimal? You have to do a lookup every time you need to convert a fraction to a decimal using a calculator? That would be like a C expert looking up how to dereference pointers or a Ruby expert looking up how to access instance variables (well, except that I've seen that too). I would think an expert witness need to testify to something more than "yep that's my result".
- PeterisP 11y ago
  Actually, yes, in many areas it is considered good practice to NEVER do things in your head even if they are obviously trivial to do so. 2x2=4, but anyway a cashier receiving or handing out 20 notes of 20 dollars should still use a calculator to get the total - since otherwise once in a blue moon a tired person will mistakenly enter it as 200. This particular combination is a "common" source of cash handling mistakes that ocassionally happens in every organization that has a lot of such deals, not a fictional example. The examples you give about programming are about understanding concepts, not menial tasks. If a programmer needs to reference a e.g. particular table/column name it often is appropriate as a policy to copy and paste it instead of retyping a dozen obvous characters; I've seen people that are paranoid enough to do that every time in production environments where testing won't catch that and you need a script to run properly the first time. Being careful and re-reading will catch most of the typos, but not all. When that's not good enough, you have to reduce risks of introducing such typos in the first place even if it takes more time to copy/paste. So yes, if you need to convert 3/16 to decimal in practical engineering situation - yes, you absolutely will use a calculator or something comparable every single time, and possibly repeat it twice to verify against typos. If you believe that you can do that in your head - sorry, you and everyone else will make a stupid mistake once every thousand times, and that is not good enough.
  - DanBC 11y ago
    But "fat finger" errors are so well known they have a name. And these are responsible for billions of dollars of errors. https://en.wikipedia.org/wiki/Fat-finger_error https://en.wikipedia.org/wiki/Fat-finger_error
  - SilasX 11y ago
    Let me reiterate: >>You have to do a lookup every time you need to convert a fraction to a decimal using a calculator? I'm not criticizing those who use a calculator to convert a fraction to a decimal. I was criticizing those who need a reference in addition to the calculator, as the witness claimed he needed. I think we're mostly in agreement.
RogerL 11y ago
All my tests were closed book. We were expected to prove/derive formulas, not use them so much. And everything that goes through a computer gets double checked with a calculator and back of envelope calculations. Otherwise you end up with crazy boners like (3 + 3/16)*20 = 68.5.
- lfowles 11y ago
  Interesting, most of my engineering classes we were allowed to bring formula sheets. Most of my math classes we were allowed to take them home and/or use open books (because neither helped if you didn't know how to prove/derive the formulas).

by chiph 11y ago

One of the things taught in engineering school is to never trust your memory. Always work from the original formulas and reference material which has been proven to be correct and to work.

SilasX 11y ago

You need a reference sheet to convert 3/16 to a decimal? You have to do a lookup every time you need to convert a fraction to a decimal using a calculator? That would be like a C expert looking up how to dereference pointers or a Ruby expert looking up how to access instance variables (well, except that I've seen that too). I would think an expert witness need to testify to something more than "yep that's my result".

PeterisP 11y ago
Actually, yes, in many areas it is considered good practice to NEVER do things in your head even if they are obviously trivial to do so. 2x2=4, but anyway a cashier receiving or handing out 20 notes of 20 dollars should still use a calculator to get the total - since otherwise once in a blue moon a tired person will mistakenly enter it as 200. This particular combination is a "common" source of cash handling mistakes that ocassionally happens in every organization that has a lot of such deals, not a fictional example. The examples you give about programming are about understanding concepts, not menial tasks. If a programmer needs to reference a e.g. particular table/column name it often is appropriate as a policy to copy and paste it instead of retyping a dozen obvous characters; I've seen people that are paranoid enough to do that every time in production environments where testing won't catch that and you need a script to run properly the first time. Being careful and re-reading will catch most of the typos, but not all. When that's not good enough, you have to reduce risks of introducing such typos in the first place even if it takes more time to copy/paste. So yes, if you need to convert 3/16 to decimal in practical engineering situation - yes, you absolutely will use a calculator or something comparable every single time, and possibly repeat it twice to verify against typos. If you believe that you can do that in your head - sorry, you and everyone else will make a stupid mistake once every thousand times, and that is not good enough.
- DanBC 11y ago
  But "fat finger" errors are so well known they have a name. And these are responsible for billions of dollars of errors. https://en.wikipedia.org/wiki/Fat-finger_error https://en.wikipedia.org/wiki/Fat-finger_error
- SilasX 11y ago
  Let me reiterate: >>You have to do a lookup every time you need to convert a fraction to a decimal using a calculator? I'm not criticizing those who use a calculator to convert a fraction to a decimal. I was criticizing those who need a reference in addition to the calculator, as the witness claimed he needed. I think we're mostly in agreement.

RogerL 11y ago

All my tests were closed book. We were expected to prove/derive formulas, not use them so much. And everything that goes through a computer gets double checked with a calculator and back of envelope calculations. Otherwise you end up with crazy boners like (3 + 3/16)*20 = 68.5.

lfowles 11y ago
Interesting, most of my engineering classes we were allowed to bring formula sheets. Most of my math classes we were allowed to take them home and/or use open books (because neither helped if you didn't know how to prove/derive the formulas).