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Accuracy
A measurement result is considered accurate if it is judged to be close to the true/acceptable value. It is a property of a single result, and is reduced by random and systematic errors.
Anomaly (outlier)
A value in a set of results that is judged not to be part of the inherent variation. When suspected, calculate the mean without the anomaly. Consider repeating the measurement if identified during the practical.
Control Variable
Variables, other than the independent and dependent variables, which are kept the same. Changes in these conditions could affect the validity of your method and results.
Dependent Variable
The variable which is measured whenever there is a change in the independent variable. Recorded as either numerical values with units (quantitative) or in the form of descriptive comments (qualitative).
Independent Variable
The variable which is deliberately changed or selected by the person in the planning of a practical activity. It is recorded in the first column of a results table.
Line of Best Fit
A line drawn on a graph that passes as close as possible to the data points. Represents the best estimate of the underlying relationship between the variables. It can be a straight line or a curve.
Precision
A quality denoting the closeness of agreement between measured values obtained by repeated measurements. Precise results are clustered together. Reducing the effect of random errors improves precision.
Random Error
Error in a measurement due to small uncontrollable effects. Cannot be corrected, but can reduce their effect by making more measurements and calculating the mean. Contributes to uncertainty.
Range (of a variable)
The maximum and minimum values of the independent or dependent variables.
Repeatability
Precision obtained when measurement results are produced in one laboratory, by a single operator, using the same conditions, over a short timescale. A measurement is repeatable when repetition under the same conditions gives similar results.
Reproducibility
Precision obtained when measurement results are produced by different laboratories and therefore by different operators using different pieces of equipment. If the results are reproducible then you can be more confident in the quality of the results.
Resolution
Smallest change in the input quantity being measured by a measuring instrument that gives a perceptible change in the reading of the measuring instrument.
Systematic Error
Error due to the measured value differing from the true value by the same amount each time. Calibrating equipment reduces systematic errors. Zero error is when the measuring device indicates a value when the quantity being measured is zero. Contributes to uncertainty.
Uncertainty
Interval within which the true value can be expected to lie, with a given level of confidence or probability. Depends on a range of factors, including systematic and random errors.
Validity (of an experiment)
Suitability of the method used to answer the question being asked. To ensure validity, identify control variables and keep them constant to avoid affecting the dependent variables.