Control & VariableAn ideal classical experiment is one in which there is only one variable, or changing, element that is being tested for. Scientists attempt to make every factor in the test consistent, or controlled, except for the variable of interest. If possible, they attempt to create a series of tests in which the quantity being tested is not changed at all, or in which the condition being tested is not present. Such a group of tests is called the control experiment or control group.
When testing whether the rate of an objects fall is related to their weight, Galileo dropped objects of different weight but maintained the same drop height in each set of experiments. When possible, it is also ideal that the shape and size of the objects be the same, so that weight is the only variable. You would also want to drop a control group - in this case several objects of the same weight - to be sure that they do not vary, so that you can state with a higher degree of certainty that your intended variable is what caused the changes.
The Communal Nature of Experimentation
Experiments performed in the modern scientific world are (or should be) done with an attitude of openness and accountability. It is crucial that any experiment involve detailed recordkeeping, in order to report the experimental results and prove the integrity of the testing procedure. When a paper is written for a scientific journal, it frequently goes through a peer-review process in which scientific experts in the discipline review the paper and its findings before being accepted for publication. (Science articles in popular magazines do not typically go through this process, though it is hopeful that the writer and editor have some level of expertise in the subject.)
Final Tips on ExperimentationI cannot reiterate enough the importance of keeping meticulous records of every aspect of a scientific test. Your first step in deciding to do a research experiment is to buy a notebook. Write down everything which you do along the way. Be sure to include the following information:
- Notes on the physics principles you're investigating, including the calculations you performed to form the hypothesis
- A complete description of the testing procedure you plan to implement, as well as any changes that take place along the way
- All supplies used, in as much detail as possible (length, weight, brand name & model #, etc.)
- Set-up of experiment, including diagrams as appropriate
- Anything that happens during the experiment which may have had an effect, whether expected (in which case it should be part of your procedure) or unexpected (weather conditions, computer locked up, knocked over a piece of equipment, etc.)
- Results from the experiment
- Conclusion based on the results and whether it supports or refutes your hypothesis