Studied by 2 people
Systematic Errors
Measurement errors in which the measurements differ from the true values by a consistent amount each time a measurement is made.
Random errors
Measurement errors in which measurements vary unpredictably and can happen when any measurement is being made.
Zero Error
The reading is not zero on a measuring device when the quantity being measured is zero (the device is faulty). This is a type of systematic error.
2 potential reasons for random errors
factors that are not controlled in the experiment
difficulty in deciding on the reading given by a measuring device.
2 potential reasons for systematic errors
the way in which measurements are taken
faulty measuring devices.
True Value
The value that would be obtained in an ideal measurement.
Measurement Error
The difference between a measured value and the true value for the quantity being measured.
Precision
How close repeated measurements are to each other - the closer they are to each other, the more precise the measurement is.
Accuracy
How close a measurement result is to the true value - the closer it is, the more accurate it is.
Uncertainty in a measurement
The interval within which the true value can be expected to lie.
Absolute uncertainty in the mean of a measurement
Approximated as half the range. This is often expressed as ± value.
Percentage uncertainty in the mean of a measurement
calculated from its absolute uncertainty and mean value as follows: % uncertainty in diameter = (absolute uncertainty) / (mean value) Ă— 100
Absolute uncertainty
Uncertainty in a measurement expressed as a numberical value.
Percentage Uncertainty
Uncertainty of a measurement expressed as a percentage of the recorded value.
Note
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