He Experimental scientific method Is a set of techniques that are used to investigate phenomena, acquire new knowledge or correct and integrate previous knowledge.
It is used in scientific research and is based on systematic observation, taking measurements, experimenting, formulating tests and modifying hypotheses. This general method is carried out not only in biology , But in chemistry , physical , geology Y Other sciences .
Through the experimental scientific method, scientists try to predict and perhaps control future events based on present and past knowledge.
Also called inductive method, it is the most used within the science by the researchers, being this part of the Scientific methodology .
It is characterized by the fact that researchers can deliberately control the variables in order to delimit the relationships between them.
These variables can be dependent or independent, being fundamental to collect the data that are extracted of an experimental group, as well as its behavior. This allows to decompose the conscious processes in their elements, to discover their possible connections and to determine the laws of those connections.
The ability to make accurate predictions depends on the seven steps of the experimental scientific method.
Phases of the experimental scientific method
1- Observations
These observations must be objective, not subjective. In other words, the observations must be able to be verified by other scientists. Subjective observations, based on personal beliefs and beliefs, are not part of the field of science.
Examples:
- Objective statement: in this room the temperature is at 20 ° C.
- Subjective statement: it is cool in this room.
The first step in the experimental scientific method is to make objective observations. These observations are based on specific facts that have already occurred and that can be verified by others as true or false.
2- Hypothesis
Observations tell us about the past or the present. As scientists, we want to be able to predict future events. Therefore, we must use our ability to reason.
Scientists use their knowledge of past events to develop a general principle or explanation to help predict future events.
The general principle is called hypothesis. The type of reasoning involved is called Inductive reasoning (Deriving a generalization from specific details).
A hypothesis should have the following characteristics:
- It must be a general principle that is maintained through space and time.
- It must be a tentative idea.
- You must agree with the available observations.
- It should be as simple as possible.
- It must be verifiable and potentially false. In other words, there must be a way to prove that the hypothesis is false, a way of refuting the hypothesis.
For example:"Some mammals have two hind limbs"would be a futile hypothesis. There is no observation that would not fit into this hypothesis! In contrast,"All mammals have two hind limbs"is a good hypothesis.
When we find whales, which have no hind limbs, we would have shown that our hypothesis is false, we have falsified the hypothesis.
When a hypothesis implies a cause and effect relationship, we state our hypothesis to indicate that there is no effect. A hypothesis, which does not affect any effect, is called the null hypothesis. For example, the drug Celebra does not help relieve rheumatoid arthritis.
3- Prediction
From the elaboration of the hypothesis that is tentative and may or may not be true, we must make a prediction about our investigation And the hypothesis.
The hypothesis should be broad and should be uniformly applied across time and space. Scientists usually can not check every possible situation where a hypothesis could be applied. For example, consider the hypothesis: All plant cells have a nucleus.
We can not examine all the living plants and all the plants that have lived to see if this hypothesis is false. Instead, we generate a prediction using a deductive reasoning (Generating a specific expectation of a generalization).
From our hypothesis, we can make the following prediction: if I examine the cells of a leaf of grass, each one will have a nucleus.
Now, let's consider the drug hypothesis: the drug Celebra does not help relieve rheumatoid arthritis.
To test this hypothesis, we would have to choose a specific set of conditions and then predict what would happen under those conditions if the hypothesis was true.
The conditions that you might want to test are the doses administered, the duration of the medication, the ages of the patients and the number of people to be examined.
All of these conditions that are subject to change are called variables. To measure the effect of Celebra, we need to perform a controlled experiment.
The experimental group is subjected to the variable that we want to test and the control group is not exposed to that variable.
In a controlled experiment, the only variable that must be different between the two groups is the variable we want to test.
Let us make a prediction based on observations of the effect of Celebra in the laboratory. The prediction is: Patients suffering from rheumatoid arthritis who take Celebra and patients taking a placebo (a starch tablet instead of the drug) do not differ in the severity of rheumatoid arthritis.
4- Experiment
We resorted again to our sensory perception to gather information. We designed an experiment based on our prediction.
Our experiment could be as follows: 1000 patients between the ages of 50 and 70 will be randomly assigned to one of two groups of 500.
The experimental group will take Celebra four times a day and the control group will take a placebo of starch four times a day. Patients will not know if their tablets are Celebra or placebo. Patients will take the medications for two months.
At the end of two months, medical examinations will be given to determine if the flexibility of the arms and fingers has changed.
5- Analysis
Our experiment produced the following results: 350 of the 500 people who took Celebra reported decreased arthritis at the end of the period. 65 of the 500 people who took the placebo reported improvement.
The data seem to show that there was a significant effect on Celebra. We need to do a statistical analysis to show the effect. Such analysis reveals that there is a statistically significant effect of the Celebra effect.
6- Conclusion
From our analysis of the experiment, we have two possible outcomes: the results match the prediction or are in disagreement with the prediction.
In our case, we can reject our prediction that the Celebra has no effect. Because the prediction is wrong, we must also reject the hypothesis on which it was based.
Our task now is to rethink the hypothesis is a form that is consistent with the information available. Our hypothesis could now be: the administration of Celebrex reduces rheumatoid arthritis compared to the administration of a placebo.
With the current information, we accept our hypothesis as true. Have we proved it to be true? Absolutely not! There are always other explanations that can explain the results.
It is possible that more than 500 patients who took Celebra would improve anyway. It is possible that more of the patients who took Celebra also ate bananas every day and that bananas improved arthritis. You can suggest innumerable other explanations.
How can we prove that our new hypothesis is true? We can never. The scientific method does not allow to prove any hypothesis.
Hypotheses can be rejected in which case this hypothesis is taken as false. All we can say about a hypothesis that resists is that we find no proof to refute it.
There is much difference between not being able to refute and prove. Make sure you understand this distinction as it is the foundation of the experimental scientific method. So what would we do with our previous hypothesis?
We currently accept it as true, but to be rigorous, we need to submit the hypothesis to more evidence that may prove to be wrong.
For example, we could repeat the experiment but change the control and the experimental group. If the hypothesis remains standing after our efforts to knock it down, we may feel more confident in accepting it as true.
However, we will never be able to assert that the hypothesis is true. Rather, we accept it as true because the hypothesis resisted several experiments to prove it to be false.
7- Results
Scientists publish their findings in scientific journals and books, in conversations at national and international meetings, and in seminars at colleges and universities.
Dissemination of results is an essential part of the experimental scientific method.
It allows other people to verify your results, develop new evidence of your hypothesis or apply the knowledge they have acquired to solve other problems.
References
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- Jevons W. The principles of science: the treatise on logic and scientific method (1958). New York: Dover Publications.
- Schafersman S. An introduction to science: scientific thinking and the scientific method (1997). Miami: Department of Geology.