The scientific method is the backbone of all rigorous scientific investigation. This method encompasses a set of techniques and principles that are designed to promote scientific inquiry and advance the accumulation of knowledge, and it has been gradually developed and refined by everyone from ancient Greek philosophers to modern-day scientists. There are some variations of the method, as well as disagreements as to how it should be used, but the basic steps are easy to understand and invaluable, not only for scientific research but also for solving everyday problems.
Part 1 of 3: Come up with a hypothesis
Step 1. Ask a question about something you observe
Curiosity is what begets new knowledge. Take note of times when you notice something that you cannot easily explain using your existing knowledge, or something that might have an explanation other than what is commonly given. Then, question how to explain the causes for which it occurs.
For example, you may have noticed that the potted plant you place on the windowsill is taller than the one in your bedroom even though the plant type is the same and you planted them at the same time.. Then you might wonder why the two plants have different growth rates
Step 2. Conduct an in-depth investigation of the knowledge that exists about the question
If you want to answer your question, it will be necessary for you to know more about the subject in question. For starters, you can read books and search for articles online about your question as a way of trying to find the answer.
- For example, if you are looking for information to answer your question about plants, to begin with, you could look up information about plant biology and photosynthesis in a science textbook or online. Gardening books and websites may also help.
- You should read as much as you can about your question, as it may have already been answered or you may find information that is helpful to formulate your hypothesis.
Step 3. Propose a hypothesis in the form of an explanation
A hypothesis is a possible explanation for the phenomenon you have observed based on your research on the subject. Basically, it is an educated guess. In the hypothesis, a cause and effect relationship must be established.
- The hypothesis needs to sound like a fact finding. For example, one possible hypothesis is that what caused the first plant to grow faster than the second was the greater amount of sunlight on the windowsill.
- Make sure it's a testable hypothesis. In other words, it needs to be something that can be tested in a scientific experiment.
Step 4. Make a prediction based on your hypothesis
You must predict an outcome that you hope to observe if the hypothesis is correct. This will be the result that you will seek to confirm in the experiment.
The prediction needs to take the form of a statement with the structure "if … then …". For example, you could say, "If a plant receives a greater amount of direct sunlight, then it will grow at a faster rate."
Part 2 of 3: Conduct the Experiment
Step 1. List the procedure for testing the hypothesis
You should make a step-by-step list of exactly what you will do to test the hypothesis. This step is not only important to ensure you are testing your hypothesis correctly, but it will also allow you and others to repeat the experiment.
- For example, you should include the exact amounts of soil that you have placed in each pot, of the water that you give each plant (and how often you do it), and of the sunlight that each plant receives (measured in watts per square meter).
- One of the key underpinnings of the scientific method is reproducibility. Therefore, it is important that you arrange the exact way in which the experiment is carried out in order to be sure that other people can copy it and try to obtain the same results.
Step 2. Identify the dependent and independent variables
The experiment must test the effect of something (the independent variable) on something else (the dependent variable). You must identify which are the dependent and independent variables and determine how you will measure them in the experiment.
For example, in the plant experiment, the independent variable would be the amount of sunlight each plant is exposed to and the dependent variable would be the height of each plant
Step 3. Design the experiment in such a way as to isolate the cause of the phenomenon
It is necessary that the experiment confirms the hypothesis or that it fails to confirm it, so it must be carried out in such a way that the cause of the phenomenon can be isolated and identified. In other words, it must be "controlled."
- For example, you could design an experiment in which you place three different plants (of the same species) in three different places: one on the windowsill, one in the same room but in an area where there is less light. direct sun and one in a dark closet. Then you would record the height each plant reaches at the end of each week over a 6 week period.
- Be careful to test only one phenomenon at a time. In all samples, all other variables must be held constant. For example, all three plants should be in pots of the same size and have the same amount and type of soil. You should also give them the same amount of water every day at the same time.
- For some complex questions, there may be hundreds or thousands of possible causes, and isolating them in a single experiment could be difficult or impossible.
Step 4. Keep impeccable records
It is necessary that other people can arrange an experiment in the same way that you have done it and obtain the same result. You must be careful that the records you keep are very thorough, documenting the experiment, the procedure you follow, and the data you collect.
It is very important that you allow other scientists to accurately copy everything you have done when repeating your experiment. In this way, they can rule out that your results arose from discrepancies or errors
Step 5. Run the experiment and collect quantified results
After designing the experiment, you will need to carry it out, taking care to collect the results in quantified metrics so that you can analyze them and that other people can try to repeat your experiment objectively.
- Continuing with the example of the plants, you must place each of them in the areas you have chosen where there are different amounts of sunlight. In case the plants themselves have grown above ground level, you should record their initial height. Then, you water each plant with the same amount of water every day, and at the end of each 7-day period, record the height of each one.
- You should run the experiment more than once to ensure that your own results are consistent and to get rid of anomalies, if any. While there is no set number of times you should repeat an experiment, you should aim to repeat it at least twice.
Part 3 of 3: Analyze and Report the Results
Step 1. Examine the data you have collected and draw conclusions from it
The hypothesis testing process is just one way to collect data that will be useful either to confirm it or not to confirm it. You must analyze your results to determine how the independent variable affected the dependent variable and whether your hypothesis is confirmed.
- To analyze your data, you can look for certain patterns or proportional relationships in your results. For example, if you observe that the plants that received more sunlight grew faster than the plant that was in the dark, you can deduce that the amount of sunlight was directly proportional to the growth rate.
- Regardless of whether or not the data confirms the hypothesis, you should always be on the lookout for other things (so-called "confounding" or "exogenous" variables) that might have had an influence on the results. If so, you may need to redesign the experiment and repeat it.
- For more complicated tests, you may not be able to determine whether the hypothesis was confirmed without first spending considerable time looking at the data you collected while testing the hypothesis.
- Also, you may find the experiment to be inconclusive if it neither confirms the hypothesis nor does it.
Step 2. Report your findings, if applicable
Scientists generally report on the results of their research in scientific journals or in conference papers. There, they not only report on their results but also on their methodology and the problems or questions that have arisen when testing their hypothesis. By reporting your findings, you allow others to use them as a basis.
- For example, you might consider publishing your findings in a scientific journal or at an academic conference hosted by a local university.
- The venue will largely determine the format in which you are going to broadcast your findings. For example, if you are presenting your findings at a science fair, a simple poster board may be sufficient.
Step 3. Conduct further investigation as necessary
In case the data couldn't confirm your initial hypothesis, it's time to come up with a new hypothesis and put it to the test. Fortunately, with the first experiment, you may have obtained valuable information to help you formulate a new hypothesis. You have to start from the beginning to keep trying to find an answer to your question.
- For example, in case, in the plant experiment, you have not found a significant relationship between the amount of sunlight received and the growth rates of the three plants, you must take into account what other variables could explain the difference in the height of the plants you witnessed earlier. These variables could be the amount of water you give each plant, the type of soil that has been used, etc.
- Even if you confirm the hypothesis after just one experiment, you will need to do further investigation as a way to ensure that the results can be reproduced and are not a one-time match.
- Understand the difference between a correlation and a causal relationship. If you confirm the hypothesis, you will have found a correlation (that is, a relationship between two variables). If other people also confirm the hypothesis, the correlation will be stronger. However, the fact that there is a correlation does not necessarily mean that one variable caused the other. In fact, if you want your project to be good, you will need to use all these procedures.
- You can test a hypothesis in different ways, the experiment of the type described above being just a simple variety. You can also test your hypothesis in the form of the double-blind method, statistical data collection, or other methods. The unifying factor is that all methods collect data or information that can be used to test the hypothesis.
- You should always let the data speak for itself. Scientists always need to be careful that their biases, mistakes, and egos do not lead to wrong results. You should always report your experiments truthfully and in detail.
- Be careful with exogenous variables. Environmental factors can intrude on even the simplest experiments and influence the results.