Scientific method refers to ways to investigate phenomena, get new knowledge, correct errors and mistakes, and test theories.
The Oxford English Dictionary states that scientific method is: "a method or procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses".
A scientist gathers empirical and measurable evidence, and uses sound reasoning. New knowledge often needs adjusting, or fitting into, previous knowledge.
Some feel this is a unreasonable method because it adds preconceived notions and biases as the result of the formation of a hypothesis might cause.
There is no one scientific method, but in general it is usually written as a number of steps:
- Come up with a question about the world. All scientific work begins with having a question to ask. Sometimes just coming up with the right question is the hardest part for a scientist. The question should be answerable by means of an experiment.
- Create a hypothesis — one possible answer to the question. A hypothesis in science is a word meaning "An educated guess about how something works". It should be possible to be prove it right or wrong. For example, a statement like "Blue is a better color than green" is not a scientific hypothesis. It cannot be proved right or wrong. "More people like the color blue than green" could be a scientific hypothesis, though, because one could ask many people whether they like blue more than green and come up with an answer one way or the other.
- Design an experiment. If the hypothesis is truly scientific, it should be possible to design an experiment to test it. An experiment should be able to tell the scientist if the hypothesis is wrong; it may not tell him or her if the hypothesis is right. In the example above, an experiment might involve asking many people what their favorite colors are. Making an experiment can be very difficult though. What if the key question to ask people is not what colors they like, but what colors they hate? How many people need to be asked? Are there ways of asking the question that could change the result in ways that were not expected? These are all the types of questions that scientists have to ask, before they make an experiment and do it. Usually scientists want to test only one thing at a time. To do this, they try to make every part of an experiment the same for everything, except for the thing they want to test.
- Experiment and collect the data. Here the scientist tries to run the experiment they have designed before. Sometimes the scientist gets new ideas as the experiment is going on. Sometimes it is difficult to know when an experiment is finally over. Sometimes experimenting will be very difficult. Some scientists spend most of their lives learning how to do good experiments.
- Draw conclusions from the experiment. Sometimes results are not easy to understand. Sometimes the experiments themselves open up new questions. Sometimes results from an experiment can mean many different things. All of these need to be thought about carefully.
- Communicate them to others. A key element of science is sharing the results of experiments, so that other scientists can then use the knowledge themselves and all of science can benefit. Usually scientists do not trust a new claim unless other scientists have looked it over first to make sure it sounds like real science. This is called peer review ("peer" here means "other scientists").
Not all scientists use the above "scientific method" in their day to day work. Sometimes the actual work of science looks nothing like the above. But on the whole it is thought to be a good method for finding out things about the world which are reliable, and is the model for thinking about scientific knowledge most used by scientists.