HOW SCIENCE WORKS - KEY WORDS

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Accuracy
A measurement result is considered accurate if it is judged to be close to the true value.
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Calibration
Marking a scale on a measuring instrument. This involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied.
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Data
Information, either qualitative or quantitative, that has been collected.
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Measurement error
The difference between a measured value and the true value.
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Anomalies
These are values in a set of results which are judged not to be part of the variation caused by random uncertainty.
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Random error
These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next. Random errors are present when any measurement is made, and cannot be corrected. The effect of random errors c
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Systematic error
These cause readings to differ from the true value by a consistent amount each time a measurement is made. Sources of systematic error can include the environment, methods of observation or instruments used. Systematic errors cannot be dealt with
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Zero error
Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero, eg the needle on an ammeter failing to return to zero when no current flows. A zero error may result in a systematic uncertainty.
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Evidence
Data which has been shown to be valid.
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Fair test
A fair test is one in which only the independent variable has been allowed to affect the dependent variable.
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Hypothesis
A proposal intended to explain certain facts or observations.
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Interval
The quantity between readings, eg a set of 11 readings equally spaced over a distance of 1 metre would give an interval of 10 centimetres.
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Precision
Precise measurements are ones in which there is very little spread about the mean value. Precision depends only on the extent of random errors – it gives no indication of how close results are to the true value.
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Prediction
A prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.
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Range
The maximum and minimum values of the independent or dependent variables; important in ensuring that any pattern is detected.
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Repeatable
A measurement is repeatable if the original experimenter repeats the investigation using same method and equipment and obtains the same results.
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Reproducible
A measurement is reproducible if the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained.
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Resolution
This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.
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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.
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True value
This is the value that would be obtained in an ideal measurement
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Uncertainity
The interval within which the true value can be expected to lie, with a given level of confidence or probability, eg “the temperature is 20 °C ± 2 °C, at a level of confidence of 95 %.
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Validity
Suitability of the investigative procedure to answer the question being asked. For example, an investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants would not be a valid procedure if th
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Valid conclusion
A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning.
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Variables
These are physical, chemical or biological quantities or characteristics.
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Categoric variable
Categoric variables have values that are labels. Eg names of plants or types of material.
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Continuous variable
Continuous variables can have values (called a quantity) that can be given a magnitude either by counting (as in the case of the number of shrimp) or by measurement (eg light intensity, flow rate etc).
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Control variable
A control variable is one which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored.
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Dependent variable
The dependent variable is the variable of which the value is measured for each and every change in the independent variable.
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Independent variable
The independent variable is the variable for which values are changed or selected by the investigator.
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Other cards in this set

Card 2

Front

Marking a scale on a measuring instrument. This involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied.

Calibration

Card 3

Front

Information, either qualitative or quantitative, that has been collected.

Card 4

Front

The difference between a measured value and the true value.

Card 5

Front

These are values in a set of results which are judged not to be part of the variation caused by random uncertainty.