Biologists, and other scientists, study the world using a formal process referred to as the scientific method. The scientific method was first documented by Sir Francis Bacon (1561–1626) of England, and can be applied to almost all fields of study. The scientific method is founded upon observation, which then leads to a question and the development of a hypothesis which answers that question. The scientist can then design an experiment to test the proposed hypothesis, and makes a prediction for the outcome of the experiment, if the proposed hypothesis is true. In the following sections, we will use a simple example of the scientific method, based on a simple observation of the classroom being too warm.
Proposing a Hypothesis
A hypothesis is one possible answer to the question that arises from observations. In our example, the observation is that the classroom is too warm, and the question taht arises from that observation is why the classroom is too warm. One (of many) hypotheses is “The classroom is warm because no one turned on the air conditioning.” Another hypothesis could be “The classroom is warm because the heating is set too high."
Once a hypothesis has been developed, the scientist then makes a prediction, which is similar to a hypothesis, but generally follows the format of “If . . . then . . . .” In our example, a prediction arising from the first hypothesis might be, “If the air-conditioning is turned on, then the classroom will no longer be too warm.” The initial steps of the scientific method (observation to prediction) are outlined in Figure 1.1.1.
Testing a Hypothesis
A valid hypothesis must be testable. It should also be falsifiable, meaning that it can be disproven by experimental results. Importantly, science does not claim to “prove” anything because scientific understandings are always subject to modification with further information. To test a hypothesis, a researcher will conduct one or more experiments designed to eliminate one or more of the hypotheses. Each experiment will have one or more variables and one or more controls. A variable is any part of the experiment that can vary or change during the experiment. The control group contains every feature of the experimental group except it is not given the manipulation that tests the hypothesis. Therefore, if the results of the experimental group differ from the control group, the difference must be due to the hypothesized manipulation, rather than some outside factor. Look for the variables and controls in the examples that follow. To test the first hypothesis, the student would find out if the air conditioning is on. If the air conditioning is turned on but does not work, then the hypothesis that the air conditioning was not turned on should be rejected. To test the second hypothesis, the student could check the settings of the classroom heating unit. If the heating unit is set at an appropriate temperature, then this hypothesis should also be rejected. Each hypothesis should be tested by carrying out appropriate experiments. Be aware that rejecting one hypothesis does not determine whether or not the other hypotheses can be accepted; it simply eliminates one hypothesis that is not valid. Using the scientific method, the hypotheses that are inconsistent with experimental data are rejected.
While this “warm classroom” example is based on observational results, other hypotheses and experiments might have clearer controls. For instance, a student might attend class on Monday and realize they had difficulty concentrating on the lecture. One observation to explain this occurrence might be, “When I eat breakfast before class, I am better able to pay attention.” The student could then design an experiment with a control to test this hypothesis.
In the example below, the scientific method is used to solve an everyday problem. Order the scientific method steps (numbered items) with the process of solving the everyday problem (lettered items). Based on the results of the experiment, is the hypothesis correct? If it is incorrect, propose some alternative hypotheses.
- Hypothesis (answer)
- The car battery is dead.
- If the battery is dead, then the headlights also will not turn on.
- My car won't start.
- I turn on the headlights.
- The headlights work.
- Why does the car not start?
C, F, A, B, D, E
The scientific method may seem overly rigid and structured; however, there is flexibility. Often, the process of science is not as linear as the scientific method suggests and experimental results frequently inspire a new approach, highlight patterns or themes in the study system, or generate entirely new and different observations and questions. In our warm classroom example, testing the air conditioning hypothesis could, for example, unearth evidence of faulty wiring in the classroom. This observation could then inspire additional questions related to other classroom electrical concerns such as inconsistent wireless internet access, faulty audio/visual equipment functioning, non-functional power outlets, flickering lighting, etc. Notice, too, that the scientific method can be applied to solving problems that aren’t necessarily scientific in nature.
This section was adapted from OpenStax Chapter 1:2 The Process of Science