Systematic error
An error that consistently occurs in the same direction and roughly the same amount every time a measurement is made.
A systematic error is an error with the system - where the system is our method for doing the experiment! It can also be an error with the measuring instrument itself - e.g. an uncalibrated scale that always reads 0.5kg too heavy.
It’s basically when our method is wrong, or will lead to misleading results because of faulty equipment.
Causes of systematic errors
- Measuring the wrong thing (e.g. measuring temperature in Celsius when you should be measuring in Kelvin)
- Using faulty or uncalibrated equipment (e.g. a scale that is not zeroed properly)
- Consistently misreading the instrument
How do systematic errors affect measurements?
A lot. The issue is that, while random errors can be reduced by taking multiple measurements and averaging them, systematic errors will always skew the results in the same direction. For example, if you’re using a scale that is not zeroed properly and always reads 0.5kg too heavy, every measurement you take will be off by 0.5kg, no matter how many times you measure it. It’s not 0.5kg in either way - it’s always too heavy.
Reducing systematic errors
To reduce systematic errors, you can:
- Calibrate your measuring instruments regularly
- Use more accurate measuring instruments
- Double-check your measurement methods to make sure you’re measuring the correct quantity
- Cross-check measurements with different instruments or methods
- Train the person doing the measurements to do the method properly
flashcards
| Question | Answer |
|---|---|
| Question / Key Term | Answer / Definition |
| What is a systematic error? | An error that consistently occurs in the same direction and roughly the same amount every time a measurement is made. |
| Systematic error is an error with what? | Error with the system (method for doing the experiment) or the measuring instrument. |
| What is an example of a systematic error from faulty equipment? | An uncalibrated scale that always reads 0.5kg too heavy. |
| What does a systematic error essentially mean? | It means our method is wrong, or will lead to misleading results because of faulty equipment. |
| What are three causes of systematic errors? | 1. Measuring the wrong thing (e.g., temperature in Celsius instead of Kelvin) 2. Using faulty or uncalibrated equipment (e.g., a scale not zeroed properly) 3. Consistently misreading the instrument |
| How do systematic errors affect measurements differently from random errors? | While random errors can be reduced by averaging multiple measurements, systematic errors always skew results in the same direction. |
| Using an uncalibrated scale that always reads 0.5kg too heavy, what happens when you take multiple measurements? | Every measurement will be off by 0.5kg, no matter how many times you measure it; it’s always too heavy. |
| List five ways to reduce systematic errors. | 1. Calibrate measuring instruments regularly 2. Use more accurate measuring instruments 3. Double-check measurement methods 4. Cross-check measurements with different instruments or methods 5. Train the person doing the measurements to follow the method properly |