Data Analysis Skills (U1) Flashcards
There is ——— in all measurements. (Fill in the blank)
- Uncertainty
How do you recognise uncertainty?
- The instrument used for the measurement
- The procedure making the measurement ( human factor)
- The environment in which the measurement is being taken
Define Accuracy?
Compares a measurement to the true value.
Define Precision?
Describe how closely measurements are to each other and how carefully measurements were made.
Define uncertainty?
The inability to actually measure a true value and the subsequent doubt created about data.
Define error?
The difference between the true value and the measurement and can’t be eliminated because of many different reasons.
What are the two basic types of error?
1) Systematic errors
2) Random errors
What is a systematic error?
Errors that affect the accuracy of a measurement.
What can systematic errors cause?
They cause readings to differ from the true value by a consistent amount each time a measurement is taken.
How do instruments come into systematic errors?
e.g. The instrument has not been calibrated properly, so the errors are consistent.
What is a random error?
Errors that effect the precision of a measurement and are always present in measurements.
What can cause random errors?
These errors are unpredictable variations in the measurement process.
What causes random errors?
e.g. estimating when measuring between increments on an instrument, sampling like sample size, and spread, parallax error , instrument sensitivity eg measuring with a metal ruler on a hot day
How can you reduce random errors?
Using an average measurement from a set of measurements, or
Increasing sample size.
How do you calculate uncertainty using analogue equipment?
1) Find the smallest increment of measurement
2) Divide by two
3) Round to 2 decimal places
