Temp measurement and accuracy

[Vaughn]

...Rick "a licensed engineer in a number of states who can stamp ground surveys that live or die on the difference between accuracy and precision" Denney

In my forestry engineering classes (public land surveying -- back in the early 70's) the instructor mentioned that many of the corners set in Humboldt County back in the 1800's were actually "set" at the corner of the bars of Eureka (and with the future President Grant probably at the same bars -- I don't think he enjoyed being stationed so far west...and so far from San Fransisco, too).

[Leigh]

Leigh, you can sure be both patronizing and disputatious. Must be part of the old-fart gig. But at least you didn't violate my expectations.

Hi Rick,

Wow. I've been accused of a number of things in my life, but this is the first time for 'disputatious'.

I thought you were talking about the position of the rings on the target, not the number of rings.

I agree with you in the latter case re precision.

- Leigh

[Leigh]

Nope. Depending on the altitude boiling point may be different from 100C.

True statement.

- Leigh

[Heroique]

Hmm. I think we’re almost there.

Can we set aside “accuracy” for a moment for this fine-tuning question:

Does a “repeatable” event always presume that someone’s definition of “precision” is being met? It’s beginning to sound to me that these two parameters are not independent from each other; one must come with the other.

The example of one arrow splitting its predecessor is “repeatable,” Leigh has explained, without the repeatable event being “precise.” (“Precision does not have a proper analog for target shooting,” he says.) But isn’t there an implicit definition of precision at work here? Namely, hitting the back end of the preceding arrow, and not missing it?

A few posts back, Rick did mention that a thermometer w/o a scale has zero precision, but is highly repeatable. But how can one make a claim for repeatability if there’s no scale at all?

[Leigh]

A few posts back, Rick did mention that a thermometer w/o a scale has zero precision, but is highly repeatable. But how can one make a claim for repeatability if there’s no scale at all?

I agree with Rick on that point.

You can draw a line on the glass with a wax marker.
If the needle always falls directly under that line, the reading is repeatable even though you don't know the actual value.

All readings are limited by the precision of the instrument, so that applies equally to the issue of repeatability.

A good example of enhanced repeatability that does not affect the precision is mirrored scales on panel meters.

You read the instrument by looking past the needle to the reflection of your eye's pupil in the mirror. When the
the needle bisects the image of the pupillary disc, your eye is lined up directly over the needle and you can read
the meter scale more accurately than if you had not corrected for parallax.

This enhanced accuracy is reflected in the spec for the meter, with mirrored-scale meters being typically 1%
as compared with the 2% spec for non-mirrored meters.

- Leigh

[E. von Hoegh]

A non mirrored meter (thermometer) can be enhanced by making a mark over the needle, on the glass. This works only for that one needle position/value though.

[E. von Hoegh]

What about the spacing of the rings on the target?

Rick "not asking for approval, and not expecting any" Denney

That will affect the scoring, not the precision/shooter of the rifle itself.

[E. von Hoegh]

Nope. Depending on the altitude boiling point may be different from 100C.


Anyway - as long as under same conditions measuring device will give same results - not really important. Can just tape up scale to the desired point even if it reads 100 at 90 - who cares as long as its 90 every time

Depending upon the altitude and barometric pressure.

[Drew Wiley]

Why an accurate thermometer is important : At 10,000 ft when water starts boiling, you
can put your finger in it and it will still be lukewarm. Your food will not cook. At sea level
if you do the same, you will have your finger for dinner. Even more important is the morning
if you like hot coffee. Maybe frivolous information to a lot of you, but after a long day on
the trail, and a cold evening arriving, I happen to like a hot meal. However, a Kodak Process thermometer is not necessary. I just wait for what is termed a "rolling boil".

[tgtaylor]

Maybe frivolous information to a lot of you, but after a long day on
the trail, and a cold evening arriving, I happen to like a hot meal. However, a Kodak Process thermometer is not necessary. I just wait for what is termed a "rolling boil".

A high altitudes a "rolling boil" (the boiling point) occurs at a lower temperature than at sea level. Any therometer can be calibrated to read accurately at any altitude/pressure by simply doing the math incorporating the barometric pressure and altitude. I'm sure that there's an app for it also.

Thomas