Lecture Notes: Accuracy and Precision

Introduction

• Uncertainty in measurements often leads to confusion in terms like accuracy and precision.
• Understanding these terms is essential when observing and recording any measurement.

Definitions

Accuracy

• Refers to how close a measured value is to the true value.
• A measurement is accurate if it closely agrees with the true value.

Precision

• Refers to the closeness of two or more measurements to each other.
• Measurements are precise if they are consistently close to each other, even if not close to the true value.

Examples and Explanation

• Example of a lab scenario measuring volume:

  • Person A’s Measurements:

    • Readings: 0.94, 0.95
    • True Value: 1
    • Analysis:
      • Precise because readings are close to each other.
      • Not accurate because readings are far from the true value.

  • Person B’s Measurements:

    • Readings: 1.05, 0.95, 1.05
    • True Value: 1
    • Analysis:
      • Neither precise nor accurate.
      • Readings are not close to each other or to the true value.

  • Person C’s Measurements:

    • Readings: 1.01, 0.98
    • True Value: 1
    • Analysis:
      • Both precise and accurate.
      • Readings are close to each other and to the true value.

Conclusion

• Multiple readings help in determining if a measurement is accurate and precise.
• A measurement is considered correct if it is both accurate and precise.
• If not, the measurement is deemed incorrect.