The Scientific Method – Hypotheses, Models, Theories, and Laws
Introduction to the Scientific Method
The scientific method is defined as the steps scientists follow to create a view of the world that is accurate, reliable, and consistent. It’s also a way of minimizing how a scientist’s cultural and personal beliefs impact and influence their work. It attempts to make a person’s perceptions and interpretations of nature and natural phenomena as scientific and neutral as possible. It minimizes the amount of prejudice and bias a scientist has on the results of an experiment, hypothesis, or theory.
The scientific method can be broken down into four steps:
- Observe and describe the phenomenon (or group of various phenomena).
- Create a hypothesis that explains the phenomena. In physics, this often means creating a mathematical relation or a causal mechanism.
- Use this hypothesis to attempt to predict other related phenomena or the results of another set of observations.
- Test the performance of these predictions using independent experiments.
If the results of these experiments support the hypothesis, then it may become a theory or even a law of nature. However, if they do not support the hypothesis, then it either has to be changed or completely rejected. The main benefit of the scientific method is that it has predictive power—a proven theory can be applied to a wide range of phenomena. Of course, even the most tested theory may be, at some point, proven wrong because new observations may be recorded or experiments done that contradict it. Theories can never fully be proven, only fully disproven.
- The Steps of the Scientific Method – A basic introduction
- What is the Scientific Method – Includes a diagram of the process
- Wikipedia’s Entry for the Scientific Method – It goes into the history of the method
- Definition of the Scientific Method – Also includes a brief history of its use
- Steps of the Scientific Method – More detail about each of the steps
Testing a hypothesis can lead to one of two things: the hypothesis is confirmed or the hypothesis is rejected, meaning it either has to be changed or a new hypothesis has to be created. This must happen if the experiments repeatedly and clearly show that their hypothesis is wrong. It doesn’t matter how elegant or supported a theory is—if it can be disproven once, it can’t be considered a law of nature. Experimentation is the supreme rule in the scientific method, and if an experiment shows that the hypothesis isn’t true, it trumps all previous experiments that supported it. These experiments sometimes directly test the theory, while other times they test the theory indirectly via logic and math. The scientific method requires that all theories have to be testable in some way—those that can’t are not considered scientific theories.
If a theory is disproven, that theory might still be applicable in some ways, but it’s no longer considered a true law of nature. For example, Newton’s Laws were disproven in cases where the velocity is greater than the speed of light, but they can still be applied to mechanics that use slower velocities. Other theories that were widely held to be true for years, even centuries, that have been disproven due to new observations include the idea that the earth is the center of our solar system or that the planets orbited the sun in perfect circular orbits rather than the now-proven elliptical orbits.
Of course, a hypothesis or proven theory isn’t always disproven by one single experiment. This is because experiments may have errors in them, so a hypothesis that looks like it failed once is tested several times by several independent tests. Things that can cause errors include faulty instruments, misreading measurements or other data, or the bias of the researcher. Most measurements are given with a degree of error. Scientists work to make that degree of error as small as possible while still estimating and calculating everything that could cause errors in a test.
- The Scientific Method and Testing Predictions – A breakdown of how to test a hypothesis
- Testing Software Hypotheses – How to apply the scientific method to software testing
- Testing Scientific Ideas – Including a graph of the process
- Research Hypothesis Testing – What is it, and how is it tested?
- What Hypothesis Testing is All About – A different look at testing
Common Mistakes in Applying the Scientific Method
Unfortunately, the scientific method isn’t always applied correctly. Mistakes do happen, and some of them are actually fairly common. Because all scientists are human with biases and prejudices, it can be hard to be truly objective in some cases. It’s important that all results are as untainted by bias as possible, but that doesn’t always happen. Another common mistake is taking something as common sense or deciding that something is so logical that it doesn’t need to be tested. Scientists have to remember that everything has to be tested before it can be considered a solid hypothesis.
Scientists also have to be willing to look at every piece of data, even those which invalidate the hypothesis. Some scientists so strongly believe their hypothesis that they try to explain away data that disproves it. They want to find some reason as to why that data or experiment must be wrong instead of looking at their hypothesis again. All data has to be considered in the same way, even if it goes against the hypothesis.
Another common issue is forgetting to estimate all possible errors that could arise during testing. Some data that contradicts the hypothesis has been explained as falling into the range of error, but really, it was a systematic error that the researchers simply didn’t account for.
- Mistakes Young Researchers Make – 15 common errors new scientists may make
- Mistakes and Negligence – An excerpt from On Being a Scientist
- Experimental Error – A look at false positives and false negatives
- Control of Measurement Errors – How to keep errors in measurement to a minimum
- Errors in Scientific Experiments – What they are and how to handle them
Hypotheses, Models, Theories, and Laws
While some people do incorrectly use words like “theory” and “hypotheses” interchangeably, the scientific community has very strict definitions of these terms.
Hypothesis: A hypothesis is an observation, usually based on a cause and effect. It is the basic idea that has not been tested. A hypothesis is just an idea that explains something. It must go through a number of experiments designed to prove or disprove it.
Model: A hypothesis becomes a model after some testing has been done and it appears to be a valid observation. Some models are only valid in specific instances, such as when a value falls within a certain range. A model may also be called a law.
Scientific theory: A model that has been repeatedly tested and confirmed may become a scientific theory. These theories have been tested by a number of independent researchers around the world using various experiments, and all have supported the theory. Theories may be disproven, of course, but only after rigorous testing of a new hypothesis that seems to contradict them.
- What is a Hypothesis? – The definition of a hypothesis and its function in the scientific method
- A Look at Scientific Models – What are they, what makes one valid, and how are they limited
- Scientific Laws and Theories – How they’re different
- Hypothesis, Theory, and Law – Definitions of each
- 10 Scientific Laws and Theories – Some examples
The scientific method has been used for years to create hypotheses, test them, and develop them into full scientific theories. While it appears to be a very simple method at first glance, it’s actually one of the most complex ways of testing and evaluating an observation or idea. It’s different from other types of explanation because it attempts to remove all bias and move forward using systematic experimentation only. However, like any method, there is room for error, such as bias or mechanical error. Of course, just like the theories it tests, the scientific method may someday be revised.