The scientific method is a systematic way of studying a problem. Use of this method is not limited solely to scientists. In fact, you have probably used the scientific method from time to time even though you were not aware of it. We can divide the scientific method into five broad categories of activity.

Identifying a Problem


A person using the scientific method must first identify a problem that needs solving. For example, a scientist may be interested in knowing whether aspirin can cure baldness in men. You as a non-scientist may be trying to decide which of two computers is better or should you take a “dietary supplement” to increase your health. These problems can also be approached in a non-scientific manner; non-science results when decisions are based on emotion, personal recommendations or television ads.

The research problem: “Can aspirin cure baldness?”

Formulating a Hypothesis


After a problem is identified within the scientific method, a hypothesis is formulated. The scientist interested in aspirin as a cure for baldness might formulate the following hypothesis: aspirin causes the regrowth of hair on completely bald heads.

Null hypothesis: “There is no significant difference in the number of hairs growing on the heads of treated or untreated men.”



Our baldness expert might design an experiment that would compare two groups of individuals so that they differed by only one factor. That difference would be whether or not they took aspirin.

Obtain 20 completely bald men. Divide them randomly into two equal-sized groups of 10 men each. One group of ten would serve as the treatment group. Send the treatment group home but tell them to take four aspirins each day for 3 months. The other group would serve as a control group—they would go home to live life as usual with no aspirin.  At the end of 3 months bring everyone back to the laboratory and count the hairs--if any--on each head.

Analyzing Data: the Results


The next step in the scientific process is data analysis. On the basis of such analyses you can either reject or accept the hypothesis that was formulated at the beginning of the experiment. The data listed below are those collected from the aspirin-baldness experiment.






Group 1.  Control: no aspirin


Number of hairs on head:

            3          6          14        2          5          7          19        30        1          2


Group 2.  Treatment: four aspirins each day


Number of hairs on head:

2          1          19        3          7          6          3          5          22        29


Does aspirin appear to affect hair regrowth? You can't really say until the data are analyzed.

The data analysis will produce results that produce statistics (characteristics related to these samples) that are interpreted as:

1. There is no significant difference in the two samples.


2. The two samples are significantly different.



            The conclusion is a statement about what the data analysis says about the hypothesis.


1. If there is no significant difference in the two samples, the aspirin treatment has had no significant effect on hair growth. Accept the null hypothesis.


2. If there is a significant difference in the two samples, the aspirin treatment has had a significant effect on hair growth. Reject the null hypothesis Aspirin does cause a regrowth of hair on completely bald heads.