On Sun, 18 Jan 2004 11:53:25 -0500, Wayne.B
wrote:

The concepts being wrestled with here are "precision" and "accuracy".

Precision implies repeatable results to some number of decimal places
plus or minus an uncertainty factor.

That is true.

Accuracy implies the correct answer in absolute terms.

Accuracy is related to how good (accurate) the data set is. For
example, "accurate within 3 meters" is not an absolute - it could
be dead on, or three meters off. Now if the phrase stated "accurate
to within 2.987654321 =/- .0000000001 meters" - that is precise - you
will always know that you will be within 2.987654321 +/- .0000000001
meters of any mark rather than somewhere within the accuracy range of
0 to 3 meters.

Now I have a headache.

Later,

Tom
S. Woodstock, CT
----------
"My rod and my reel - they comfort me."

St. Pete, 12 Lb. Test

snip
The concepts being wrestled with here are "precision" and "accuracy".

Precision implies repeatable results to some number of decimal places
plus or minus an uncertainty factor.

That is true.

Accuracy implies the correct answer in absolute terms.

Accuracy is related to how good (accurate) the data set is. For
example, "accurate within 3 meters" is not an absolute - it could
be dead on, or three meters off. Now if the phrase stated "accurate
to within 2.987654321 =/- .0000000001 meters" - that is precise - you
will always know that you will be within 2.987654321 +/- .0000000001
meters of any mark rather than somewhere within the accuracy range of
0 to 3 meters.

snip
I work with precision measuring devices and find that these are slippery
concepts for most people. The shoddy day-to-day usage and close relationship
between the two words does not make things any easier.
See:
http://www.ieee-uffc.org/freqcontrol...g/vigaccur.htm
for a nice intuitive explanation of the difference between accuracy and
precision.

Mark Browne

"Mark Browne" wrote in message
news:xcEOb.80651$sv6.188571@attbi_s52...
snip
The concepts being wrestled with here are "precision" and "accuracy".

Precision implies repeatable results to some number of decimal places
plus or minus an uncertainty factor.

That is true.

Accuracy implies the correct answer in absolute terms.

Accuracy is related to how good (accurate) the data set is. For
example, "accurate within 3 meters" is not an absolute - it could
be dead on, or three meters off. Now if the phrase stated "accurate
to within 2.987654321 =/- .0000000001 meters" - that is precise - you
will always know that you will be within 2.987654321 +/- .0000000001
meters of any mark rather than somewhere within the accuracy range of
0 to 3 meters.

snip
I work with precision measuring devices and find that these are slippery
concepts for most people. The shoddy day-to-day usage and close
relationship
between the two words does not make things any easier.
See:
http://www.ieee-uffc.org/freqcontrol...g/vigaccur.htm
for a nice intuitive explanation of the difference between accuracy and
precision.

Mark Browne



Really bad when I make the mistake on an explanation posting. Used to teach
Digital Signal Processing and programming for Texas Instrument fixpoint
DSP's.
Bill

On Sun, 18 Jan 2004 22:58:41 GMT, "Mark Browne"
wrote:

snip
The concepts being wrestled with here are "precision" and "accuracy".

Precision implies repeatable results to some number of decimal places
plus or minus an uncertainty factor.

That is true.

Accuracy implies the correct answer in absolute terms.

Accuracy is related to how good (accurate) the data set is. For
example, "accurate within 3 meters" is not an absolute - it could
be dead on, or three meters off. Now if the phrase stated "accurate
to within 2.987654321 =/- .0000000001 meters" - that is precise - you
will always know that you will be within 2.987654321 +/- .0000000001
meters of any mark rather than somewhere within the accuracy range of
0 to 3 meters.

snip
I work with precision measuring devices and find that these are slippery
concepts for most people. The shoddy day-to-day usage and close relationship
between the two words does not make things any easier.
See:
http://www.ieee-uffc.org/freqcontrol...g/vigaccur.htm
for a nice intuitive explanation of the difference between accuracy and
precision.

That was interesting - I was going to use rifle accuracy as an
example.

Actually, I was bored stiff yesterday and wanted to play with the
concept a little.

Oh well - back to the grind. :)

It's tough being retired.

Later,

Tom
S. Woodstock, CT
----------
"My rod and my reel - they comfort me."

St. Pete, 12 Lb. Test