The Get to Know You Game...

[Jadis]

sometimes when you are just trying to avoid the same questions over and over.. strange things come to mind.

do you think that's accurate?

[odims_sphere]

no this is accurate:

"Accuracy" redirects here. For the song "Accuracy" by The Cure, see Three Imaginary Boys

In the fields of science, engineering, industry and statistics, accuracy is the degree of conformity of a measured or calculated quantity to its actual (true) value. Accuracy is closely related to precision, also called reproducibility or repeatability, the degree to which further measurements or calculations show the same or similar results. The results of calculations or a measurement can be accurate but not precise; precise but not accurate; neither; or both. A result is called valid if it is both accurate and precise. The related terms in surveying are error (random variability in research) and bias (non-random or directed effects caused by a factor or factors unrelated by the independent variable).

Contents [hide]

1 Accuracy vs precision - the target analogy

2 Accuracy and precision in logic level modeling and IC simulation

3 Quantifying accuracy and precision

4 Accuracy in biostatistics

5 References

[edit] Accuracy vs precision - the target analogy

High accuracy, but low precision

High precision, but low accuracyAccuracy is the degree of veracity while precision is the degree of reproducibility. The analogy used here to explain the difference between accuracy and precision is the target comparison. In this analogy, repeated measurements are compared to arrows that are fired at a target. Accuracy describes the closeness of arrows to the bullseye at the target center. Arrows that strike closer to the bullseye are considered more accurate. The closer a system's measurements to the accepted value, the more accurate the system is considered to be.

To continue the analogy, if a large number of arrows are fired, precision would be the size of the arrow cluster. (When only one arrow is fired, precision is the size of the cluster one would expect if this were repeated many times under the same conditions.) When all arrows are grouped tightly together, the cluster is considered precise since they all struck close to the same spot, if not necessarily near the bullseye. The measurements are precise, though not necessarily accurate.

Further example, if a measuring rod is supposed to be ten yards long but is only 9 yards, 35 inches measurements can be precise but inaccurate. The measuring rod will give consistently similar results but the results will be consistently wrong.

However, it is not possible to reliably achieve accuracy in individual measurements without precision — if the arrows are not grouped close to one another, they cannot all be close to the bullseye. (Their average position might be an accurate estimation of the bullseye, but the individual arrows are inaccurate.) See also Circular error probable for application of precision to the science of ballistics.

[edit] Accuracy and precision in logic level modeling and IC simulation

As described in the SIGDA Newsletter [Vol 20. Number 1, June 1990] a common mistake in evaluation of accurate models is to compare a logic simulation model to a transistor circuit simulation model. This is a comparison of differences in precision, not accuracy. Precision is measured with respect to detail and accuracy is measured with respect to reality. Another reference for this topic is "Logic Level Modelling", by John M. Acken, Encyclopedia of Computer Science and Technology, Vol 36, 1997, page 281-306.

[edit] Quantifying accuracy and precision

Ideally a measurement device is both accurate and precise, with measurements all close to and tightly clustered around the known value. The accuracy and precision of a measurement process is usually established by repeatedly measuring some traceable reference standard. Such standards are defined in the International System of Units and maintained by national standards organizations such as the National Institute of Standards and Technology.

Precision is usually characterised in terms of the standard deviation of the measurements, sometimes called the measurement process's standard error. The interval defined by the standard deviation is the 68.3% ("one sigma") confidence interval of the measurements. If enough measurements have been made to accurately estimate the standard deviation of the process, and if the measurement process produces normally distributed errors, then it is likely that 68.3% of the time, the true value of the measured property will lie within one standard deviation, 95.4% of the time it will lie within two standard deviations, and 99.7% of the time it will lie within three standard deviations of the measured value.

This also applies when measurements are repeated and averaged. In that case, the term standard error is properly applied: the precision of the average is equal to the known standard deviation of the process divided by the square root of the number of measurements averaged. Further, the central limit theorem shows that the probability distribution of the averaged measurements will be closer to a normal distribution than that of individual measurements.

Get it?

[Jadis]

not at all....

shouldn't you be doing something else right now?

[odims_sphere]

not at all....

shouldn't you be doing something else right now?

Sleeping..

Shouldn't we all be doing something else right now?

[creatureofthenyte]

Yes, I should be on the road going to work right now.

Odim, did you clean your house yet ?

[Jadis]

Yes, I should be on the road going to work right now.

Odim, did you clean your house yet ?

no, he didn't clean it... he wants it to clean itself

do you think that could happen?

[Msterbeau]

In the future, everything will self clean.

Do you want to become an unproductive blob?

[Jadis]

sometimes I feel that way at my job... heh. but no, I don't wanna be.

is the force strong in you?

[diana2di]

force... what force... oh you mean the jedi force!

nah not in me... at least not all the time...

but then who is the force strong in anyways?

[Jadis]

I couldn't tell ya since I've yet to see an entire Star Wars movie from start to finish... *shrugs*

Do you think you know who the next president will be?

[EvilEve]

hopefully the lesser of two evils...

does this really concern you?

[Msterbeau]

It should concern us all.

Does the status quo suck?

[EvilEve]

only sometimes...

do you sing when no one's looking?

[Msterbeau]

And when they're looking. I do give them the option of ear protection, though.

Do you need some?

[EvilEve]

if you sound like a dying animal, i'll put you out of your misery then i'll sing just to show you HOW it's done...

sound like a good idea?

[Msterbeau]

I'd rather listen to good singing then bad. Except...if you put me out of my misery, I can't hear it.

Can we skip that part?

[diana2di]

sure we don't have to put you out of your misery... there is such a thing as duct tape and crazy glue... we can crazy glue your lips together around a straw and you can eat and drink until it wears off... hopefully when we aren't around.

does that sound like a good idea?

[Msterbeau]

No. Then I can't kiss.

Can I just not sing in front of you?

[damagedangel]

Maybe I want you to sing.

Will you dance too?

[littlepinkkitty]

because this is what it feels like when doves cry?

are u afraid of birds?

[Msterbeau]

Only the ones with great big claws.

What are you afraid of?

[EvilEve]

that 'boy' won't like me...

is that a resonable fear?

[Msterbeau]

No. There are many boys. Probably more then a few that you could be very compatible with.

Am I being to positive here?

[creatureofthenyte]

No, it is always good to have a positive outlook, especially in the realm of romance

[DeadBurgerKing (10)]

Didn't ask a question...

Huh?