MathTeacher did you get the answer to your question to your satification?
"So how should the uncertainty be interpreted and presented".
Your post was dealing with EDMI measurements and posted on Sunday, January 18, 2015, at 1356 hrs.
JOHN NOLTON
Tombstone, AZ.
PS When is your retirement PARTY and where? Good Luck.
Well, yes, to some extent. With no specific instructions from manufacturers, the introduction of an ISO standard on some manufacturers spec sheets, and specifications for operations such as CBL establishment including an interpretive statement, I think the question is still open.
As in all statistics problems, the real question is which model fits the situation. In the absence of a definitive statement, I think it's reasonable to choose the most restrictive interpretation, but everyone is free to make their own choices.
Thanks for asking about the retirement party. As far as I know, none is planned, although my successor has been hired and I want to spend next week helping her to shift from the world of a consulting systems analyst to that of a mathematics teacher. Talk about training issues, they are huge in education and getting more difficult every day. Once the bell rings and the door closes, it's the teacher and the students, ready or not.
You are correct in HOW to calculate the uncertainty BUT as you say you must check with the manufactures manual to see HOW he specify the performance of his EDMI. Some give accuracy and some give precision.
As for the NGS manual you made a link to they do it correctly. On page 10 the first
equation gives delta = [0.0017^2 + (D*10^-6)62]^1/2
The first part 0.0017 is given by assigning a error of +/- 1mm to the Instrument setup and +/- 1mm for the prism setup and +/- 1mm for the EDMI; so if you take the square root of the sum of the square of the 3 errors you will get the square root of 3 and that is 1.7mm or 0.0017 as they show. The next term is just 1ppm.
I would like to say that there are several TYPO errors in the NOS NGS 8 Memorandum;
One is on page 4, 1st line under Introduction," beganEarly" ; they need a space between the 2 words.
The other TYPO is on page 8, last line just above Monumentation; "to establishment of the baseline" The last word is spelled base line.
Both errors have been turned in. If any body finds more just turn them into your State Geodetic Advisor and he will do the rest.
There is one more thing; On page 12 1st line under Instrumentation; "accuracy NTE 1 millimeter". I did not know what NTE is but found out by a call to NGS. It stands for NOT TO EXCEED.
One last thing NGS uses a Wild DI2002 (2 of them) for base line work.
JOHN NOLTON
Tombstone, AZ.
Exactly. And NGS chooses base line distances that cancel part of the error accounted for by the constant term, something that's not always an option for a surveyor. But, NGS recognizes that the remainder of that constant piece is itself a standard deviation, which matches the interpretation of some, but not all, other sources.
Now if equipment manufacturers would state their specs in the format that NGS uses, there would be no doubt.
John, at the risk
of being called anal, I point out that there is a typo and a grammar error in your post.
"If any body finds more just turn them into", has both. "Anybody" is one word and there should be a comma after the word, "more".
😉
JRC
John, at the risk
> of being called anal, I point out that there is a typo and a grammar error in your post.
>
> "If any body finds more just turn them into", has both. "Anybody" is one word and there should be a comma after the word, "more".
>
> 😉
>
> JRC
Egads.
😉
John, at the risk
You're right, but that didn't cross my threshold for correcting a forum post. Unfortunately, I see worse in newspapers, nowadays.
