Measuring Equipment - Does Uncertainty = Accuracy ?

Is Uncertainty and Accuracy the same?

  • Same absolutely !

    Votes: 3 37.5%
  • not even close, NOPE !

    Votes: 5 62.5%
  • opposite

    Votes: 0 0.0%

  • Total voters
    8
G

George Weiss

#1
I was on a PMEL forum site where it seemed as if there was a 50% bet that they are opposites, and 50% bet that they were equals. I am interested in knowing what the trueth is. Is it just semantics?
 
Elsmar Forum Sponsor
S

Sturmkind

#2
Re: Does Uncertainty = Accuracy ?

Hi, George1Weiss!

The AIAG definitions from the 4th edition Measurement Systems Analysis manual are:

Accuracy "The closeness of agreement between an observed value and the accepted reference value." (page 213)
-Often visually depicted as a cluster of hits on a bullseye target that are 'off-center'.

Uncertainty "...the range assigned to a measurement result that describes, within a defined level of confidence, the limits expected to contain the true measurement result. Uncertainty is a quantified expression of measurement reliability." (Page 218)

- A range is not accuracy (though it may be associated with Precision (page 216).

-IMO the true measurement result would be bias point estimate (minus) the accepted reference value bounded by the upper and lower Uncertainty confidence interval attributed to the measureand (Page 215).

Worthwhile question, that!
 
G

George Weiss

#3
Re: Does Uncertainty = Accuracy ?

I have seen the bullseye target with the close pattern of points, being placed somewhere other than center. This suggests an error of measure or source. The target center is Idea, (true measurement point), versus actual of the pattern off-center. If there was no uncertainty/error, then might there be a pattern at center? I guess, since we will not be perfect, then Precision comes into play. So unless accuracy and Precision are infinite, there will be uncertainty? Opposites?
Accuracy = Bias = 1/uncertainty?
 
Last edited by a moderator:

Statistical Steven

Statistician
Staff member
Super Moderator
#4
Re: Does Uncertainty = Accuracy ?

I have seen the bullseye target with the close pattern of points, being placed somewhere other than center. This suggests an error of measure or source. The target center is Idea, (true measurement point), versus actual of the pattern off-center. If there was no uncertainty/error, then might there be a pattern at center? I guess, since we will not be perfect, then Precision comes into play. So unless accuracy and Precision are infinite, there will be uncertainty? Opposites?
Accuracy = Bias = 1/uncertainty?
Accuracy is an estimate of the mean. How close is the mean to the target.

Uncertainity is an estimate of the variability or precision.

You have 3 states of measurement

Accurate but uncertain - meaning that on average we get the target by any inidividual measurement is uncertain.

Inaccurate but certain - meaning that on average we are off target (some call it a bias) and the individual measurements are close and certain.

Accurate and certain - Everytime we measure we are close to the target. The ideal state!

That is my interpretation.
 
G

George Weiss

#5
Re: Does Uncertainty = Accuracy ?

From this I gather:
in sourcing or measuring:
Uncertainty = 1/certainty = 1/precision.
The accuaracy = bias, and not uncertainty.
SO assuming 0 bias, uncertainty = 1/precision,
and when uncertainty = 0, then precision is infinite, or IDEA value (perfect)?
Pardon my less-than-Webster description(s).
 

Statistical Steven

Statistician
Staff member
Super Moderator
#6
Re: Does Uncertainty = Accuracy ?

From this I gather:
in sourcing or measuring:
Uncertainty = 1/certainty = 1/precision.
The accuaracy = bias, and not uncertainty.
SO assuming 0 bias, uncertainty = 1/precision,
and when uncertainty = 0, then precision is infinite, or IDEA value (perfect)?
Pardon my less-than-Webster description(s).
I believe Uncertainity would be 1-certainity.
 
K

kaikai

#8
Re: Does Uncertainty = Accuracy ?

ISO uses Accuracy for trueness (systematic error) and precision (random component). Accuracy fall in the category of "Error aproach".

On the other hand, Uncertainty is defined by GUM, and it belongs the category of "Uncertainty Approach".

So, it is very difficult to compare these terms directly. But roughly speaking the word Accuracy is an antonym of the word Uncertainty.
 

Jim Wynne

Staff member
Admin
#9
Re: Does Uncertainty = Accuracy ?

So, it is very difficult to compare these terms directly. But roughly speaking the word Accuracy is an antonym of the word Uncertainty.
Calling accuracy and uncertainty antonyms is a sort of category error. If "accurate" refers to the proximity of a measured quantity to the "true" value (and it does in this context), then uncertainty, again in this narrow context, is a quantification of the probable difference. These are in no way opposite; uncertainty is a way of defining accuracy.
 
D

dv8shane

#10
Re: Does Uncertainty = Accuracy ?

If all the contributors have the exact same types of distribution such as rectangular for the accuracy, and floor specifications they could, but the actual uncertainty must include the resolution uncertainty of the unit under test. This is one of the things that is most often over looked. Picture calibrating a 4 digit meter with an 8 digit calibrator the uncertainty component of the calibrator is dominated by the resolution uncertainty of the meter and you must include this contributor as part of the measurement system.
 
Thread starter Similar threads Forum Replies Date
D Does 7.6 Control of Monitoring and Measuring Equipment align with ISO 17025 ISO 17025 related Discussions 4
D Calibration labels - Does all measuring equipment require a label to indicate status? General Measurement Device and Calibration Topics 8
M Missing measuring equipment General Measurement Device and Calibration Topics 6
B Measuring and monitoring equipment - Understanding which procedures to be compliant with ISO 13485 ISO 13485:2016 - Medical Device Quality Management Systems 6
E ISO 13485 7.6 Control of monitoring and measuring equipment - Assess the Validity ISO 13485:2016 - Medical Device Quality Management Systems 4
G Posting Measuring Equipment Accuracy for User Information General Measurement Device and Calibration Topics 4
S ISO 9001 7.1.5.2 - Actions Taken When Measuring Equipment is Found to be Unfit for Use General Measurement Device and Calibration Topics 13
C AS9100D 7.1.5.2 / Calibration of Employee Owned Measuring Equipment AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 5
johnny johnson New measuring equipment selection (Cg/Cgk) Capability, Accuracy and Stability - Processes, Machines, etc. 2
Claes Gefvenberg Worst measuring equipment ever? Coffee Break and Water Cooler Discussions 6
A Calibration Interval - AS9100 - Control of Monitoring and Measuring Equipment Calibration Frequency (Interval) 8
R Auditing Fitness of Purpose for Monitoring and Measuring Equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
rob73 Advice/recommendations for equipment to measure a soft pvc tube - Optical Measuring? General Measurement Device and Calibration Topics 4
H Tolerance, decimal places, and measuring equipment capability Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
Q Scope in procedure and content for 7.6 Monitoring and Measuring Equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 13
L Inspection Equipment Accuracy - Measuring the diameters of small holes Measurement Uncertainty (MU) 5
x-files ISO 9001 Clause 7.6 - Test as Measuring Equipment... ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
S Measuring OEE (Overall Equipment Effectiveness) for each Job, not for Machine Lean in Manufacturing and Service Industries 2
M GRR approach for off line Measuring Equipment Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
G Control of Monitoring and Measuring Equipment for Servicing Photocopiers ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
S ISO9001 Exclusion 7.6 Control of Monitoring and Measuring Equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 16
B Meaningful MSA Study on Viscosity Measuring Equipment IATF 16949 - Automotive Quality Systems Standard 14
P I need to Borrow or Hire a Surface Roughness (Ra) Measuring Equipment Manufacturing and Related Processes 3
W Moving M&TE (Measuring & Test Equipment) to New Facility General Measurement Device and Calibration Topics 3
M 7.6 Control of Monitoring and Measuring Equipment - Monitoring vs. Measuring IATF 16949 - Automotive Quality Systems Standard 2
GStough Human Capital: How to Meet Requirements of 7.6 (Monitoring/Measuring Equipment)? Service Industry Specific Topics 10
R ISO 17025 M&TE (Measuring & Test Equipment) Calibration Requirements ISO 17025 related Discussions 4
Anerol C Uncertainty Excel Spreadsheets for Measuring Equipment wanted Measurement Uncertainty (MU) 5
G 7.6 Control of Monitoring and Measuring Equipment vs. 7.6.1 Measurement Systems Analy IATF 16949 - Automotive Quality Systems Standard 15
J Measuring and Test Equipment that must undergo MSA Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 8
Roberticus Gage R & R to different Specifications on Departmental Measuring Equipment Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 25
C Measuring Equipment on Injection Machine should be Calibrated by 3rd party? General Measurement Device and Calibration Topics 21
A Non-Contact Measuring Equipment Recommendations wanted General Measurement Device and Calibration Topics 4
P Is it compulsory to send new measuring equipment for calibration / verification? Calibration Frequency (Interval) 3
Q Soldering and AS9100 - Are soldering irons "monitoring and measuring equipment"? AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 10
B Looking for a Standard identifying SME's (Standard Measuring Equipment) General Measurement Device and Calibration Topics 1
M Basis used for Calibration or Verification of Measuring Equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
N Control of Measuring and test Equipment - Flowchart wanted ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 10
D How to Protect Measuring Equipment from Damage and Deterioration ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
I Clarification of ISO 9001: 2008 Section 7.6 - Monitoring and measuring equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 12
G ANSI/NCSL Z540.3 (Requirements for the Calibration of Measuring and Test Equipment) General Measurement Device and Calibration Topics 1
D Control of monitoring and measuring equipment - infrared thermometer for cross-check ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
W Computer Software - ISO 9001 Clause 7.6 Control of Monitoring and Measuring equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
J How can measuring equipment deteriorate? (Re: 7.6) ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
J Configuration Management - ISO 9001 - 7.6 Monitoring and Measuring Equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 5
P Repetition (sample size) for measuring equipment accuracy determination General Measurement Device and Calibration Topics 1
S Health care, social services and measuring equipment Service Industry Specific Topics 6
S Measuring Equipment and Monitoring Equipment - Verification ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 17
hogheavenfarm Extending control of measuring equipment ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
A Is Calibration Required for Equipment/Devices Used for Measuring Support Services General Measurement Device and Calibration Topics 6

Similar threads

Top Bottom