Does Converting Measurement Units Affect Error Values?

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SUMMARY

The discussion centers on the impact of unit conversion on error values in measurements. A student converted a distance measurement from centimeters to meters, adjusting the associated error from 0.05 cm to 0.0005 m. The teaching assistant (TA) argued that the error cannot decrease simply due to unit conversion, despite the student asserting that the percentage error remains unchanged. Ultimately, the consensus is that while the numerical representation of the error changes with unit conversion, the actual uncertainty in the measurement does not diminish.

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  • Understanding of basic measurement concepts and uncertainty
  • Familiarity with error propagation principles
  • Knowledge of unit conversion techniques
  • Basic statistics, particularly percentage error calculations
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Students in scientific fields, laboratory technicians, and anyone involved in data analysis and measurement accuracy will benefit from this discussion.

LikwidN2
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I'm trying to do a lab writeup, and I'm going to include the uncertainty values as part of the data table. I was measuring distances with a meter stick with smallest divisions of 1mm, and estimated the error to be .05cm (.5mm - half the smallest division, as our TA told us was a good rule of thumb). However, having the data in (cm) was not useful, so I simply converted to (m), and the error along with it - the error of .05(cm) became an error of .0005(m). The TA, checking our data before we left the lab, told me that the conversion was wrong - that error can't get smaller just because you up-converted the data. I thought this was crazy because %error is still the same. She even pointed out the error propagation tables, showing me that the error for Z = a(B) ± C is dZ = a(dB), which seems to prove my point, not hers. Who is right?
 
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You are right. The error didn't change. Just the units.
 

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