Differences Among Experts Regarding the Expression of Measurement Uncertainty
Confusion with terminology
Drawing conclusions from experimental data is the foundation of physics
Different conventions are used to report measurement uncertainties
What is the meaning of ± 5 in m = 75 ± 5 g ?
Measurement uncertainty experts
Different standards for x ± ?x based on expert opinions:
Do these measurements agree? x = 20 ± 5, y = 30 ± 5
Do these measurements agree? x = 30 (?x= 1), y = 40 (?y= 5)
Are these exam averages different? A = 70 ± 15, B = 76 ± 14 (N = 50 students)
But if we consider the standard error: A = 70 ± 2, B = 76 ± 2
Suppose that a voter-exit poll finds candidate A is favored over B with a 53% majority (± 4% margin of error).
Assuming margin of error is ± 1?:
Survey polls typically report a 95% confidence level (± 2?)
Conclusion from poll vote:
PPT Slide
ISO Guide, p.7
ISO recommended practice: Avoid ± notation and explain clearly.
How many significant figures?
“Remember to include units!”
Email: Duane_Deardorff@ncsu.edu
Home Page: www.ncsu.edu/PER
Other information: APS Centennial Mtg, March 99, Atlanta