practical terms Flashcards
Define accuracy
A measure of the closeness of an individual test result and the true value
If a test result is accurate it is close to the true value
Define Precision
The closeness of agreement between measured values obtained by repeated measurements.
(Precise results may not be accurate)
Define resolution
The smallest change in the quantity being measured that can be detected by an instrument.
e.g. a typical mercury thermometer will have a resolution of 1°C, but a typical digital thermometer will have a resolution of 0.1°C
Define anomaly
Is a value in a set of results that does not fit the trend and different to other repeats.
Define repeatability
Repeatability is the precision obtained when results are produced over a short timescale by one person using the same equipment in the same place.
Define reproducilibity
Reproducibility is the precision obtained when results are produced over a wider timescale by different people using equivalent equipment in different places
Define uncertainity
Any measuring apparatus has uncertainty.
The uncertainty is often taken to be half a division on either side of the smallest unit on the scale you are using.
Example – if a pipette has graduations to mark every 0.1cm3, the uncertainty of the pipette is _______
Define random errors
Due to judgment errors made by the experimenter
Can be reduced by repeating the procedure several times
Define systematic errors
Errors may be inherent in the equipment and repeated with every replicate.
If the percentage error is known, a calculation can done to determine the margin of error.
Define validity
A measurement is valid if it measures what it is supposed to be measuring.
You can increase thevalidityof anexperimentby controlling more variables, improving measurement technique, increasing randomisation to reduce sample bias and adding a control
