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