1.4–1.10: A beginner’s guide: what are the steps of the scientific method?

Eugenie Clark (at left), a pioneering investigator of shark behavior since the 1940s.

“Scientific method”—this term sounds like a rigid process to follow, much like following a recipe. In practice, however, the scientific method is an adaptable process that can be done effectively in numerous ways. This flexibility makes the scientific method a powerful process that can be used to explore a wide variety of thoughts, events, or phenomena, not only in science but in other areas as well.

The basic steps in the scientific method are:

• Step 1. Make observations.
• Step 2. Formulate a hypothesis.
• Step 3. Devise a testable prediction.
• Step 4. Conduct a critical experiment.
• Step 5. Draw conclusions and make revisions.

Once begun, though, the process doesn’t necessarily continue linearly through the five steps until it is concluded (FIGURE 1-5). Sometimes, observations made in the first step can lead to more than one hypothesis and several testable predictions and experiments. And the conclusions drawn from experiments often suggest new observations, refinements to hypotheses, and, ultimately, increasingly precise conclusions.

Figure 1.5: The scientific method: five basic steps and one flexible process.

An especially important feature of the scientific method is that its steps are self-correcting. As we continue to make new observations, a hypothesis about how the world works might change (FIGURE 1-6). If our observations do not support our current hypothesis, that hypothesis must be given up in favor of one that is not contradicted by any observations. This may be the most important feature of the scientific method: it tells us when we should change our minds.

Figure 1.6: Hold the fries. We apply an understanding of science when we choose foods from the menu that have fewer calories and less saturated fat.

Because the scientific method is a general strategy for learning, it needn’t be used solely to learn about nature or scientific things. In fact, we can analyze an important criminal justice question using the scientific method:

• How reliable is eyewitness testimony in criminal courts?

For more than 200 years, courts in the United States have viewed eyewitness testimony as unassailable. Few things are seen as more convincing to a jury than an individual testifying that she can identify the person she saw commit a crime (FIGURE 1-7). But is eyewitness identification always right? Can the scientific method tell us whether this perception—or some other commonly held idea—is supported by evidence? As we describe how to use the scientific method to answer questions about the world, it will become clear that the answer is a resounding yes. In the coming sections of this chapter, we also look at how the scientific method can be used to address a variety of issues. In addition to our criminal justice question, we’ll answer two additional questions:

• Does echinacea reduce the intensity or duration of the common cold?
• Does shaving hair from your face, legs, or anywhere else cause it to grow back coarser or darker?

Figure 1.7: “With your own two eyes …”? How reliable is eyewitness testimony in criminal courts?