From The Scientific Method of Problem Solving [
http://www.howe.k12.ok.us/~jimaskew/pmethod.htm ], a control group is
explained thusly: "First, proper controls must be incorporated into
each experiment. A control group receives the same treatment as the
experimental group except that the factor being tested is applied to
the experimental group only, not to the control."
from "control group study, double-blind, random tests" [
http://skepdic.com/control.html ] they explain control groups as
follows: "A control group study uses a control group to compare to an
experimental group in a test of a causal hypothesis. The control and
experimental groups must be identical in all relevant ways except for
the introduction of a suspected causal agent into the experimental
group. If the suspected causal agent is actually a causal factor of
some event, then logic dictates that that event should manifest itself
more significantly in the experimental than in the control group."
From "SIEM H1 Research: Scientific Method" [
http://www.unep.ch/islands/siemh1.htm ], they explain control groups
as follows: "The design of a good experiment is not always as easy as
it seems. There should be only one possible cause of the result of an
experiment, that will either prove or disprove your explanation. If
more than one interpretation is possible, then your question will not
be answered (except perhaps by another experiment)...
Often it is necessary to do an experiment and a control. A control
should be just like the experiment, but without changing the thing you
want to test. If a doctor wants to test a medicine, he may take two
groups of similar people, and give the medicine to one group while the
other group (the control) gets similar looking pills without the
medicine. No one (often not even the doctor) will know which is which
until after the test. This is because people often get well just
because they think they are taking a good medicine, and even the
doctor might unconsciously judge the results differently if he knew
which patients were taking the real medicine. The control group makes
it possible to prove that the medicine made a real difference."
Some of the previous quotes integrate more than just the concepts of
control. The "double-blind" study is also referenced as a method of
assuring the integrity of your results.
To analyze the quotes I gave you, the concept of a control group in
scientific studies is as follows:
When you perform a scientific study, you are attempting to acertain a
certain quality of an object or system. In order to assure that the
quality you are testing for is the only thing that is affected in your
experiment, you conduct 2 tests. Both tests are identical, except for
the one quality you are testing for. Thusly, if you are testing the
ability of different paints to help wood withstand the elements for
example, you would have one piece of wood for each paint that you are
testing, plus one more that is not treated with paint. each piece of
wood would be exactly the same, with each kind of paint added to one
piece of wood, and one piece of wood not treated at all, and each
piece of wood would be subjected to the same conditions. The wood that
is untreated would be the control group, and would serve to be a
baseline to compare with the results of the other group. The various
pieces of wood with the paint on them are known as the experimental
group, and would be compared against the control group. The idea here
is to be able to verify the validity of your results.
search strategy:
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=scientific+method+control+groups
://www.google.com/search?q=general+science+scientific+method+control+groups&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off
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