3.25 Determining Uncertainty

• Percentage uncertainty for a single reading (measured value) is defined by the equation:

Percentage uncertainty = × 100 %

1. Determine the absolute uncertainty

• • The absolute uncertainty of the reading is half the resolution of the analogue voltmeter

= 0.1 V

2. Calculate the percentage uncertainty

× 100 % = 0.67 %

• The percentage uncertainty in measurements from multiple readings (e.g., repeat readings) use half the range of the readings
  • The range of the readings is the difference between the highest and lowest reading

1. Calculate the mean value 

mean ω = = 0.153 rad s^–1

2. Calculate half the range (this is the uncertainty for multiple readings)

× (0.159 – 0.147) = 0.006 rad s^–1a

3. Calculate percentage uncertainty

× 100 % = × 100 %

× 100 % = 3.92 %