Scientific Method Step 4- Performing an Experiment

When a hypothesis has been established and predictions made, a controlled experiment is designed and carried out. There are many principles which must be followed when performing a scientific experiment. The experiment is said to be controlled if it is shown that all other variables which could have an effect on the outcome are controlled. 

This is done through the use of a control group and an experimental group. The control group is the same as the experiment group other than the fact that the experimental group is subjected to the variable on which the experiment is based. This allows for a reliable experiment.

An experiment must be designed and explained so that any scientist looking at it would be able to perform it and bring about the same results. In biological and chemical experiments, sterile (absence of micro-organisms) or septic (minimum amount of micro-organisms present) conditions are used.

Double blind testing is used where the control and experimental groups are unaware which group they are in, removing the placebo effect(where the administration of a medicine leads to a person feeling better due to psychological effects). The experiment will prove true or false the hypothesis clearly.

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