accuracy vs. precision?

[cjolley]

Originally posted by Sethos
PS. the drunk answer tends to be 11

But if it's ALWAYS 11 then it's precise. No?
chuck

[Wulfman]

yes, somehow.

reminds me of chemistry (analytical)...

mfg
wulfman

[Novdid]

Originally posted by cjolley
But if it's ALWAYS 11 then it's precise. No?
chuck

Now you're reaching!

[agallag]

Ok, enough examples already!

Once and for all:

Precision = repeatability
Accuracy = correctness

Now quit it!

[Chrono_Wanderer]

learn this in school before... i think intrepreting this in Math/science will help...

Accuracy is how close you are to the "right" number/value

Precision is the "approximation" you work with. i.e. lots of decimals is more precise. It doesn't necessarily has to be accurate.

For example... in one experiment, the theoretical yield is 12.

An accurate answer will be 11.

A precise answer, but not accurate answer is 0.00000000475147181.

A precise AND accurate answer will be 12.00000000000000001

An infinitely precise answer is 12. (infinite significant digits)

[Chrono_Wanderer]

Originally posted by agallag
Ok, enough examples already!

Once and for all:

Precision = repeatability
Accuracy = correctness

Now quit it!

No way man! Gotta do some Postcount++;

[agallag]

Originally posted by Chrono_Wanderer
No way man! Gotta do some Postcount++;

Ok then... uh... is my postcount 1711, or 1451.938744237475234985?

[agallag]

...and who needs postcount with a userid number of 19? That's right, I r0x0r!! ph34r m3!!!!

[cjolley]

Originally posted by Novdid
Now you're reaching!

Just pointing out the problem with using repeatability as a definition for precision.

Suppose I have two instruments:

Gizmo1 can measure a 2x4 to within 1/4".
Gizmo2 can measure a 2x4 to within 0.00001".

Take a board about 72" long and measure it 3 times with each.

Gizmo1 gets: 72", 72", 72"
Gizmo 2 gets: 72.00321", 71.98213", 72.00912"

You would never say that Gizmo1 was more precise than Gizmo2.

Gizmo1 is more consistent than Gizmo2 precisely () because it is less precise!

The operative concept is just like significant digits.
How finely divided is the ruler.

Chuck

PS postcount++

[agallag]

Yeah, what he said...

postcount++

[Gurm]

Actually, you WOULD say that Gizmo2 is more precise.

- Gurm

[az]

I believe that's what Chuck said

AZ

[KvHagedorn]

Good grief.

There are degrees of precision but only one accurate.

For example, 3 x 3 = 9... this is accuracy (to an infinite degree of precision)

Now, tell me how long this board is.. accurately. You cannot. Why? Well, you are comparing something real and tangible with an accepted standard of measurement.. it is not possible to give a truly accurate answer. Is it a trillion three thousand and two atoms long? Which atoms at what point? At what point in the orbits of those electrons are you measuring? See? Even utterly INCREDIBLE levels of precision will not yield the absolute.. that is, an ACCURATE answer.

[Paddy]

Happy now Jon?

[cjolley]

Re: accuracy vs. precision?

Originally posted by jonnylane
I was told that this could be a question in an interview for a job i applied for: What is the difference between accuracy and precision?....

Then there is the Monty Python answer.
"Do you mean when they are used as nouns or as adverbs?"

Chuck