What is the "Scientific Method"

The scientific method is how scientists do what scientists do to find reliable answers to their questions about how nature works. Basically, the scientific method is the process that scientists most often use to make sure they aren't fooling themselves.

The scientific method involves the following steps: investigating something that interests you, identifying the problem, making your best guess about what the solution might be, devising a test to see if you can prove the guess WRONG (scientists don't try to prove themselves right! They know that making sure they aren't fooling themselves means trying to prove their guesses wrong). Then you must carry out your test, and finally you must analyze your results and reach a conclusion.

Investigation: Investigation is the process of gathering information about something that interests you from every reliable source that you can find. These sources can include your own experiences, respected experts, printed and web-based resources, or the results of experiments done by others. Ultimately, this research should lead you to learn about something you don't understand, or to a question you have that doesn't seem to be answered by anything you've learned about. It is from these questions that you will select your science fair project idea.

Question/Hypothesis: The question you select to answer must be one that both interests you and is very narrowly focused. It should be an open-ended question, that is, one that is answered with a statement, or better, a graph, rather than a simple yes or a no. For example, "How does temperature affect the reproduction of beer yeast?"

Note how narrowly focused this question is. It's about the life process of yeast—reproduction; one type of yeast—beer yeast; and one factor that affects its growth—temperature. To find the answer to a broader question such as "How does temperature affect yeast?" you would have to test different life processes and lots of different types of yeasts.

Hypothesis: A hypothesis is your best educated guess about what the answer to your question is likely to be. And of course, you can't make an educated guess without an education. Your hypothesis has to be based on your knowledge, experience and/or the research you did about the subject that lead to your question.

Personally, I do not think that students should be required to state a hypothesis for their experiment. Many times, when entering some new area of research, scientists have very little idea about what result a new experiment may produce. Their attitude is "Let's do this and see what happens." A hypothesis is NOT essential to an experiment. Worse, it changes the focus of the experiment from answering an open question, to defending a their opinion. And that often leads students to fit the facts to their opinions, instead of fitting their data to their question. In short, it leads to dogma over data, instead of data over dogma.

However, if your science fair competition insists that you formulate a hypothesis, then make your best guess, then try your darnedest to prove that guess wrong! If you have absolutely no idea what will happen, then let your guess be the "null hypothesis"--the most boring possible hypothesis--the guess that the variables you are testing in your experiment are not related. That is the best way to make sure you are not fooling yourself.

Whatever you do, don't change your hypothesis even if data do not support it. If you've disproved your hypothesis--good for you! You've got the makings of a real scientist! If time permits, repeat or redesign to verify your refutation and the judges will really take note of your work.

Do the experiment!

Of course, the experiment is the process you go through to answer your question or challenge your hypothesis. You take data to see how different things are related. Anything you decide to measure in your experiment is called a variable, (meaning "something that can change"). There are three kinds of variables that you must to identify in your experiment: independent, dependent, and controlled.

The independent variable whatever you decide to change in your experiment. The dependent variable is the variable you monitor to see how it responds to that change. A controlled variable is one that you make absolutely certain not to change during the experiment. It's important to only allow one variable to change at a time so we can isolate how one thing affects one other thing. It is only be studying these simple on-against-another kinds of interactions that we can wrap our minds around exactly what's going on.

Looking at our example of temperature on beer yeast, the independent variable is temperature and the dependent variable is yeast reproduction.

Control Experiments: Often, scientists need to do mini experiments before they do their main experiment to make sure they don't get blindsided by other conditions in the experiment. One important mini test is called a "control experiment" in which the independent variable is kept constant in order to identify other things that can cause the dependent variable to change. In a control, you set up the experimental you intend to do, but you don't allow your independent variable to change. Instead, you allow other parts of the experiment to change (for example, the amount of light that falls on the yeast). Doing control tests allow you to know how hard you have to struggle in your experiment to keep these variables constant. For example, if you discovered that the yeast growth rate wasn't much affected by atmospheric pressure, then you know you wouldn't have to worry if a storm front moved it. However, if you discovered that the grow rate was affected by light, then you'd want to make sure that you didn't expose the yeast to enough light during your main experiment to affect the results.

In principle, there are many variables that want to do control experiments to study; humidity, air pressure, light, temperature, and so on. There is no way you are going to be able to test them all. Those that you can't test you'll want to keep as constant as you reasonably can, and then note what you did in your logbook. No science fair judge could possibly expect you to conduct every possible control experiment. Professional scientists don't. Rather, they rely on their experience to tell them what variables they need to control and which are less important.

Another thing, don't just assume you everything right the first time. If you want to make sure you're not fooling yourself you need to repeat the experiment a couple of times to verify that you get essentially the same result every time. If not, then your results are being affected by some subtle variable that you haven't controlled for properly. Chasing these down can be a frustrating exercise, but it is here that you'll really learn the artistry of the scientist.

Conclusion: The conclusion is a summary of the results of your experiment and your final statement of how the data bare on your question or hypothesis. If the data prove your hypothesis wrong (scientists say "falsify the hypothesis") then great! If you see how others could take this work further, make sure end by pointing out how. Namely, say what independent variable you'd use next time, what you would be careful to control, and what change you'd be looking for in the dependent variable.

Dr. Shawn

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Comments

[sciencedude]

Thanks! This has proven to be very useful for my science coursework! especially the variables part, it was really helpul!

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Well how many hypothesis does a study need?

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