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An accurate measurement is one which is close to the true value.
Define: Anomalous data
Anomalous data are those measurements that fall outside the normal, or expected, range of measured values.
When using a measuring instrument, calibration involves fixing known points and constructing a scale between these fixed points.
Define: Confounding variable
- A confounding variable is one that may, in addition to the independent variable, affect the outcome of the investigation.
- Confounding variables must be kept constant or the investigation will not be a fair test.
Define: Control experiment
An experiment that is set up to eliminate the possibility that something else other than the independent variable might have produced the results that were obtained.
Define: Control group
- A group that is treated in exactly the same way as the experimental group except for the factor that is being investigated.
- This allows scientists to make a comparison.
- It ensures that the data that are collected are valid because any differences between the results for the experimental group and those for the control group will be due to a single independent variable.
Define: Double-blind trial
- A trial in which neither participant or researcher is aware of the treatment each participant is receiving
- This reduces the effect of bias and increases validity
The data or observations that are used to support a given hypothesis or belief.
Define: Fair test
- A test in which only the independent variable has been allowed to affect the dependent variable
- All other variables have been controlled or kept constant
The smallest scale division on the measuring instrument that is being used.
Define: Random distribution
A random distribution is one that arises as a result of chance
- The results of an investigation may be considered reliable if they can be reproduced in further tests
- The reliability of data within a single investigation can be improved by carrying out repeat measurements.
Define: Systematic errors
- Errors that cause readings to be spread about some value other than the true value.
- In other words, all the readings are shifted in one direction from the true value.
- Systematic errors may occur when using a wrongly calibrated instrument.
- Data are only valid if the measurements that have been made are affected by a single independent variable only.
- They are not valid if the investigation is flawed and control variables have been allowed to change or there is observer bias.
- Conclusions are only valid if they are supported by valid and reliable data measured to an appropriate level of accuracy.
Define: Zero errors
Errors caused by instruments that have an incorrect zero