GCSE Science ISA Glossary

Question	Answer
Fair test	A fair test is one in which only the independent variable has been allowed to affect the outcome of the experiment.
Hypothesis	A proposal intended to explain certain facts or observations.
Interval	The quantity between readings, e.g. a set of 11 readings equally spaced over a distance of 1 metre would give an interval of 10 cm.
Prediction	A prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.
Systematic error	These cause readings to differ from the true value by a constant amount each time a measurement is made. Sources of systematic errors can include the environment, methods of observation or instrument used. Systematic errors can't be dealt with by simple repeats. If a systematic error is suspected, the data collection should be repeated using a different technique or a different set of equipment, and the results compared.
Range	The maximum and minimum values of the independent or dependent variables; important in ensuring that any pattern is detected. For example a range of distances can either be quoted as : "From 10 cm to 50 cm" or "From 50 cm to 10 cm"
Repeatable	A measurement is repeatable if the original experimenter repeats the investigation using the same method and equipment and obtains the same results.
Reproducible	A measurement is reproducible if the investigation can be repeated by a different person, or by using different equipment or technique and obtaining the same results.
Resolution	The smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.
Sketch graph	A line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables. It will not have any points plotted and although the axes should be labelled they may not be scaled.
True value	This is the value that would be obtained in an ideal measurement.
Dependent variable	The dependent variable is the variable of which the value measured for each and every change in the independent variable.
Uncertainty	The interval within which the true value can be expected to lie, with a given level of confidence or probability, at a level of 95%.
Validity	Suitability of the investigation procedure to answer the question being asked. For example, an investigation to find out the rate of a chemical reaction depended upon the concentration of one of the reactants would not be a valid experiment because the temperature of the reactants aren't controlled.
Variables	Physical, chemical or biological quantities or characteristics.
Categoric variables	Categoric variables have values that are labels. E.g. names of plants.
Continuous variable	Continuous variables can have values that can be given a magnitude either by counting or by measurement.
Control variable	One which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept at a constant or at least be measured.
Accuracy	A measurement is considered accurate if it is judged to be close to the true value.
Calibration	Making a scale on a measuring instrument. This involves establishing the relationship between indications on a measuring instrument and standard or reference quantity values, which must be applied.
Data	Information, either qualitative or quantitative, that has been collected.
Measurement error	The difference between a measured value and the true value.
Anomalies	These are values in a set of results which are judged to not be part of the variation caused by random uncertainty.
Random error	These cause reading to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next. They are present when any measurement is made and can't be corrected. The effect of random errors can be reduced by making more measurements and calculating a new mean.
Zero error	Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero, e.g. the needle on an ammeter failing to return to zero when no current flows. A zero error may result in systematic uncertainty.
Evidence	Data which has been shown to be valid.

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GCSE Science ISA Glossary

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	Created by Aisha Ojany almost 9 years ago