Language of Measurement Flashcards
What is Accuracy?
A measurement is considered accurate if it is judged to be close to true value
Accuracy of an experiment is described how?
- It is not quantifiable (no numbers to describe accuracy)
It is describes as less or more accurate
Accuracy of an experiment are dependant on which type of error/effects?
Both systematic and random errors
What is Precision?
A quality denoting the closeness of agreement between measured values obtained by repeated measurements.
Simple terms - How close acquired results are to each other
Describe what can be infered from precision of an experiment:
High Precision
* Less randome errors
* Controlled variables remained controleed and consistent
Low Precision
* High random errors
Precision does not indicate how close values are to true value
How can Precison be described?
Can be described numerically by measurements of imprecision
Eg: Standard deviation
What is Resolution?
The smallest change in quantity that an instrument can detect
What is Gradation?
The gradation is the marked changes on analogoue instruments (Eg: A burette has gradation of 0.1mL is there is a line for every 0.1mL)
Describe what is the extent of measurements obtained from analogue instruments in terms of resolution
Analogue intruments wll have resolution to a maximum of half the gradation
(Eg: If gradation is 1mL, then resolution is 0.5mL)
Describe what is the extent of measurements obtained from digital instruments in terms of resolution
Digital instruments will have resolution to a maximum number of decimal places
(Eg: If balance can measure to 3 decimal places, then resolution is 0.001g)
What is True Value?
Value that would be obtained in an ideal measurement
Describe the characteristics of the true value
- Considered unknowable
- In special case of a fundamental constant, the constant is considered to have a true value.
What are some examples of known true values/fundamental constants
- Molar Gas Constant
- Avogadro Constant
- Molar Volume of ideal gas at SLC
What does Repeatability refer to?
The ability to achieve the same or very similar results consistently if experiment is performed again.
Describe some things that contribute to high repeatability
- Same experimenter
- Same equipment
- Same conditions
- Same location
- Same technique
- Successive measurement over a short period of time
High repeatbility is linked to what aspect of measurement?
High precisions
If there is high precision = high repeatability
What is Reproducibility
Ability to achieve same or very similar results if experiment performed by someone else
Describe some factors that can impact the reproducibility of an experiment:
- Difference in experimenter
- Difference in equipment
- Difference in conditions
- Difference in location
- Technique may vary or be the same
High reproducilibility is linked to what aspect of measurement?
High Accuracy
If high accuracy = high reproducibility
