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2 Experimental investigations
These types of studies usually involve the collection of data in a process
when there is some manipulation of a variable that are assume to affect
the outcome of a process being studied. This usually involves keeping other
variables fixed as far as possible. For example, investigating plants to
see how they respond to different levels of fertilisers. Or an experiment
may involve testing humans to see how they respond to a new drug.
In many cases the same statistical analysis can be used with either
observational or experimental data. However the validity of any inferences
that result from the analysis depend very much on the nature of the data.
An effect that is seen consistently in replications of a well designed
experiment can only reasonably be explained as being caused by the
manipulation of the experimental variables. With an observational study
the same consistency of results might be obtained because all the data are
affected in the same way by some unknown unmeasured variable. The “
obvious” explanation for an effect that is seen in the results of an
observational study may be quite wrong.
Some experiments cannot be performed either because the variables involved
are not controllable or because the experiment is unethical. For example,
suppose that a medical researcher wants to study the relationship between
the levels of certain air pollutants and the incidence of cancer in
cities. Changing the levels of pollutants in cities would probably not be
possible with resources of the researcher, and, even if it could be done
increasing levels on purpose would be unethical. Hence the only study
possible may be one involving analysing the prevailing levels of
pollutants in the atmosphere and cancer rates, with an attempt being made
to allow for the possible effects of some other factors that are thought to
influence cancer rates.
This is a broad discussion on the two types of research and in higher
studies these can be further divided into more groups.
Planning and carrying out research study
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Types of Research
Observational Research
Investigations
Planning
Working Scientifically
Observations
Observation Questions
Hypothesis Formation
Experimental Design
Aspects
Ethics
Types of Research
Data Analysis |
