How science works

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  • Created on: 02-04-12 16:37
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HOW SCIENCE
WORKS ­ A
GLOSSARY OF
TERMS
Accuracy An accurate measurement is one which is close to the true value.
Anomalous data Anomalous data are those measurements that fall outside the normal, or
expected, range of measured values. Variation is a characteristic of all
living
organisms, and it is often difficult in biological investigations to
distinguish
between data that reflect this variation and those that are genuinely
anomalous. A large number of readings allows anomalous data to be
identified with greater certainty.
When using a measuring instrument, calibration involves fixing known
Calibration points
and constructing a scale between these fixed points.
Causal link A change in one variable that results from or is caused by a change in
another variable
Chance is essentially the same as luck. If a coin is tossed in the air,
Chance whether
it comes down heads or tails is purely due to chance. The results of any
investigation could have a genuine scientific explanation but they could
be
due to chance. Scientists carry out statistical tests to assess the
probability of the results of an investigation being due to chance.
Confounding A confounding variable is one that may, in addition to the independent
variable, affect the outcome of the investigation. Confounding variables
variable must

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In some
investigations, ecological investigations in particular, it is not always
possible
to keep confounding variables constant. In such cases, these variables
should be monitored. In this way it may be possible to decide whether
or not
the factor concerned affects the outcome of the experiment.
Confounding
variables are sometimes referred to as control variables.
A control experiment is one that is set up to eliminate certain
Control possibilities.…read more

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Dependent The dependent variable is the variable the value of which is measured for
variable each change in the independent variable.
Double-blind trial A trial, usually used in the context of medicine, when assessing the effects of
a new drug or treatment on humans. Neither the patients nor the scientists
concerned know which treatment a particular individual is receiving until after
completion of the trial. This helps to avoid bias and increase the validity of
the trial.…read more

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Placebo A placebo is a dummy pill or injection given to members of a control group
in medical trials. Where a placebo is in the form of a pill, it should be identical
to the pill used with the experimental group. The only difference should be
that that the placebo does not contain the drug being trialled. The use of
placebos helps to ensure that the data collected from a trial are valid.…read more

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Probability
Protocol
Random
distribution
Random errors
Raw data
Reliability
Systematic errors
True value…read more

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Validity
Zero errors
Probability is the likelihood of an event occurring. It differs from chance in that it can be expressed
mathematically. In statistical tests, probabilities are usually expressed as a decimal fraction of one.
Thus a probability of 0.05 means that an event is likely to occur 5 times in every 100.
Once an experimental method has been shown to produce valid and reliable results, it becomes a
protocol used by other scientists.…read more

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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.
Zero errors are caused by instruments that have an incorrect zero.…read more

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