absolute error (1 Viewer)

[ballin]

hey im just curious about absolute error, heres my example:

lets say my mean result is 40.00

i conduct 5 repetitions, the largest deviation from the mean is 37.00.

in a question, i am required to record the MAX deviation from the mean, i.e. the absolute error. obviously it is going to be 3.00, but if i write - 3.00, am i wrong?

 

[jyu]

hey im just curious about absolute error, heres my example:

lets say my mean result is 40.00

i conduct 5 repetitions, the largest deviation from the mean is 37.00.

in a question, i am required to record the MAX deviation from the mean, i.e. the absolute error. obviously it is going to be 3.00, but if i write - 3.00, am i wrong?

If the largest deviation is 37.00, it should be recorded as 37 and the mean result is 40, not 37.00 and 40.00 respectively.

The measurement is 40 +/- 3, the absolute error is 3 (not -3).

 

[ballin]

THAT IS FUCKING BS. how can you say that the absolute error is 40 + / - 3 ??? thats BS, what if the highest positive deviation was say... 42?? then it wouldnt be 40 +/- 3. i really dont think i should lose freakin marks just because i indicated which direction the max deviation was. its irrelevant, particularly when you're calculating relative error, which we were asked to do in the next part.

 

[airie]

THAT IS FUCKING BS. how can you say that the absolute error is 40 + / - 3 ??? thats BS, what if the highest positive deviation was say... 42?? then it wouldnt be 40 +/- 3. i really dont think i should lose freakin marks just because i indicated which direction the max deviation was. its irrelevant, particularly when you're calculating relative error, which we were asked to do in the next part.

Actually, absolute error is half of your limit of reading. The max deviation from your mean should be compared to the absolute error, and whichever is more should be noted as the error of your measurement in your final report.

And error of a measurement indicates a range in which the actual value could fall, the uncertainty resulting from inevitable human errors and the fact that your instruments are not 100% precise. And since your final reported error should allow the greatest deviation that could result, you SHOULD report your measurement as 40 +/- 3, as your max deviation from the mean is 3 (and I'm assuming that the absolute error - half the limit of reading - is smaller than this, since you made no mention of it).

 

[ballin]

ok, i understand that. but im trying to get the marks because i worked within the limits of the question. this was the question

Using the following information, work out the absolute error for each mean in your experiment:

Absolute Error = max deviation from the mean.

Using this data alone, im quite confident that i can argue that i should still get the marks because i put a minus in front of all my absolute errors. Thats the only information they gave us, so my argument is - using THAT formula, my answers should be correct. Yay or nay?

 

[airie]

Using this data alone, im quite confident that i can argue that i should still get the marks because i put a minus in front of all my absolute errors. Thats the only information they gave us, so my argument is - using THAT formula, my answers should be correct. Yay or nay?

Where's the formula?

The error of measurements always gives a range of values that the actual measurement could be, ABOUT the mean value. So yes, you do need the +/- sign, instead of just a - sign. Otherwise you're stating that your values fall in the range of 37 to 40, instead of 37 to 43, the latter actually allowing the max deviation to occur.

(And btw, the max deviation is always positive - it is the "deviation", you know )

 

[helper]

ok, i understand that. but im trying to get the marks because i worked within the limits of the question. this was the question

Using the following information, work out the absolute error for each mean in your experiment:

Absolute Error = max deviation from the mean.

Using this data alone, im quite confident that i can argue that i should still get the marks because i put a minus in front of all my absolute errors. Thats the only information they gave us, so my argument is - using THAT formula, my answers should be correct. Yay or nay?

NAy

Simple. If you say the value is 5 and an error of -1, then you are saying the value is between 4 and 5

If you say the value is 5 and the error is +/- 1, the value is between 4 and 6. Two different answers.

 

[jyu]

NAy

Simple. If you say the value is 5 and an error of -1, then you are saying the value is between 4 and 5

If you say the value is 5 and the error is +/- 1, the value is between 4 and 6. Two different answers.

Absolute error is 3, 40 +/- 3
Relative error is 3/40
%error is (3/40)x100% = 7.5%, 40 +/- 7.5%