Science Inquiry Skills

Last updated Sep 5, 2023 Edit Source

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• Accuracy
  • How close your experimentally derived number is to the “true” or “real” quantity being measured
• Validity
  • No other variables, known or unknown, are impacting the independent or dependent variables
• Reliability
  • Getting similar results after repeating trials
• Precision
  • How the repeat values or a given trial are to each other or the fineness of the scale on the instrument being used to take measurements

• Uncertainty which is a property of the measuring instrument

  • Unavoidable

• Give the error value with the recorded value

  • e.g. $3.00 \pm 0.005 cm$

• Absolute Error ($A\\ u$) =  the smallest unit of scale on the instrument

  • $A\\ u$ = half the smallest unit of scale on the instrument
  • Absolute error will be the same for every measurement taken by a given instrument

• Percentage error ($%\\ u$)

  • $%\\ u = \frac{A\\ u}{measurement} \times 100%$

• Rules for measurement uncertainty:

  1. If adding or subtracting measurements add the absolute errors
  2. If multiplying or dividing measurements add the percentage errors

• Impacts each trial in the same direction away from the true value
  • Bias in direction

• Impacts each trial but with no bias in direction, and if truly random, should cancel out with respect to accuracy