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.
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?”
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.
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.