Lesson 1, Topic 1
In Progress

01-Scientific Method

April 12, 2021

What we often call the scientific method is merely a systematic approach to discovery. Although there is no single method for scientific discovery, some scientists follow the steps outlined in Figure 1-1 to discover the concepts of human biology discussed in this textbook.

First, one makes a tentative explanation, called a hypothesis. A hypothesis is a reasonable guess based on previous informal observations or on previously tested explanations.

After a hypothesis has been proposed, it must be tested—a process called experimentation. Scientific experiments are designed to be as simple as possible to avoid the possibility of errors. Often, experimental controls are used to ensure that the test situation itself is not affecting the results.
For example, if a new cancer drug is being tested, half the test subjects will get the drug and half the subjects will be given a harmless substitute. The group getting the drug is called the test group, and the group getting the substitute is called the control group. If both groups improve, or if only the control group improves, the drug’s effectiveness has not been demonstrated. If the test group improves, but the control group does not, the hypothesis that the drug works is tentatively accepted as true. Experimentation requires accurate measurement and recording of data.
If the results of experimentation support the original hypothesis, it is tentatively accepted as true, and the researcher moves on to the next step. If the data do not support the hypothesis, the researcher tentatively rejects the hypothesis. Knowing which hypotheses are incorrect is as valuable as knowing which hypotheses are valid. Scientists can thus focus on the ideas shown to have merit and avoid wasting time with disproven hypotheses.

Initial experimental results are published in scientific journals so that other researchers can benefit from them and verify them. If experimental results cannot be reproduced by other scientists, then the hypothesis is not widely accepted. If a hypothesis withstands this rigorous retesting, the level of confidence in the hypothesis increases. A hypothesis that has gained a high level of confidence is called a theory or law.

Why is it important to know the steps of experimentation and developing theories if your main interest is a career in science applications—such as a health career? If you do not understand how concepts are discovered and how they can change after additional experimentation, it is hard to fully grasp them.

The facts presented in this textbook are among the latest theories of how the body is built and how it functions. As methods of imaging the body and measuring functional processes improve, we find new data that cause us to replace old theories with newer ones.