Percent difference and uncertainty

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SUMMARY

The discussion focuses on calculating the percent difference and associated uncertainty between two measurements: 0.282 ± 0.0019 and 0.288 ± 0.04, using the formula for percent difference. The correct method involves adding uncertainties for subtraction and converting uncertainties into percentages for division. The average value used in the calculations is 0.285 ± 0.02. Participants emphasize the importance of showing attempts to facilitate effective problem-solving discussions.

PREREQUISITES
  • Understanding of basic statistics, specifically uncertainty propagation
  • Familiarity with the concept of percent difference
  • Knowledge of measurement error and its representation
  • Ability to perform arithmetic operations with uncertainties
NEXT STEPS
  • Research "Uncertainty propagation in measurements" to understand how to combine uncertainties
  • Learn "Percent difference calculations" to apply the formula effectively
  • Explore "Error analysis techniques" for a deeper understanding of measurement accuracy
  • Study "Statistical methods for data analysis" to enhance problem-solving skills in similar contexts
USEFUL FOR

Students in physics or engineering, educators teaching measurement and uncertainty, and anyone involved in experimental data analysis.

mike2601
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Homework Statement



How do we solve this problem?
% Difference = (l 0.282 +/- 0.0019 - 0.288 +/- 0.04 l) / 0.285 +/- 0.02

Homework Equations


Percent Difference = (l value - average value l) / average value x 100%

The Attempt at a Solution



many attempts made but cannot get correct uncertainty for the answer
 
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Welcome to PF, Mike.
You are supposed to show your attempt(s) so we have some idea what method you are supposed to use, and to avoid giving solutions to people who haven't tried the problem on their own.

For the subtraction, I would add the uncertainties.
For the division, I would convert the uncertainties into per cents of the main values, add the per cents, and finally find that % of the main value.
 

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