×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Term for normalized percent error?

Term for normalized percent error?

Term for normalized percent error?

(OP)
Is there a term for percent error type calculations when using the full scale value as the denominator instead of the actual value? Using percent error results in very high values when the actual quantities are small.

For example on a line rated at 500 MW with an error of 10 MW, what would I call the calculation that results in 2% for both of these cases:
assuming a calculated flow of 10 MW and an actual flow of 20 MW
% error = 50% =abs(10 MW-20 MW)/20 MW
% ????? = 2% =abs(10 MW-20 MW)/500 MW

assuming a calculated flow of 490 MW and an actual flow of 500 MW
% error = 2% =abs(10 MW-20 MW)/20 MW
% ????? = 2% =abs(490 MW-500 MW)/500 MW

RE: Term for normalized percent error?

If you are talking about instrument measurement accuracy, they are rated by percent of full scale. The reason you do not use instruments to measure values that are one percent of full scale is that the percent error in actual reading will be huge.

RE: Term for normalized percent error?

(OP)
Getting into the weeds a bit, I am looking to flag components of a large power grid simulation if the calculated power flows are significantly different than measured power flows. The full scale measurements for various components range a couple of orders of magnitude from about 1 MW for a small generator to over 5000 MW for large transmission path.

RE: Term for normalized percent error?


Quote (Bacon)

what would I call the calculation that always gives 2%
I would call it (politely) an incorrect calculation

RE: Term for normalized percent error?

Consider:

The speeding ticket 80 km/h in a posted 40 km/h Zone.

Ferraro Enzo ZXX owner "Top speed of my car is 395 km/h. (80-40)/395 is barely more than 10% over the limit."

Tata Nano owner "Top speed of my car is 110 km/h. (80-40)/110 36% over the limit! Man I was really flying!"

Who pays the higher fine?

Bonus question: Who pays the higher fine as a percentage of their income?

RE: Term for normalized percent error?

I was told that in Italy, it's not how fast you drive, but who you manage to pass along the way.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Term for normalized percent error?

(OP)
Although percent error is useful for many things, I cannot use it in this case because sometimes the actual flows are zero when the simulated flows are non zero, leading to a divide by zero error.

Mint,
Does my edited post make more sense? I agree that a calculation that always had the same result would be wrong.

Your bonus question is quite on the point. It uses the percent Full Scale of the owners income rather than using percent error.

RE: Term for normalized percent error?

In Austria, the fine you in accordance with your ability to pay.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close