Chapter 2. A template for scientific inquiry

Five elements

Five elements are found in most applications of the scientific method. Understanding these elements will enable you to understand both how to use the scientific method and its limitations. In template form, these 5 elements are:

It is easiest to understand these concepts by way of examples, so we will consider two formal science examples below: cancer associated with living near nuclear power plants, and birth defects caused by alcohol consumption in pregnant women.

Nuclear power plants

Epidemiologists in Britain noted that the rates of certain types of cancers were more common in people who lived near nuclear power plants than in the population at large. The obvious conclusion from such a finding was that the power plant actually caused the increase in cancer (because of radiation). However, epidemiologists kept looking at more data and eventually noted an unexpected pattern that changed their view: higher cancer rates also existed in sites that had been selected for nuclear power plants but in which the plants had not been built. Thus, it was likely that the higher cancer rates surrounding the nuclear power plants had existed before the plant was built and so were not caused by the plant.

This simple example contains all five elements of our template:

Goal. The goal is to identify (and ultimately reduce) environmental causes of cancer.

Models: The most conspicuous model - and the one of greatest concern -is that a nuclear plant is the cause of increased cancer rates. It is a model because it is a description of what might be occurring in and around the nuclear power plants.

Data. The data are merely the cancer rates in people living in different locations. Data were analyzed in two sets, however. Set 1: cancer rates in people living near power plants and cancer rates in the population at large. Set 2: cancer rates in people living at sites selected for construction but where the plant was not yet built.

Evaluation. The model is fairly specific about which groups of people should show elevated cancer rates, so the evaluation can be performed without any sophisticated analysis: the model can only explain higher cancer rates around existing power plants. The first set of data is consistent with both models, whereas set 2 is not consistent with the model.

Revision. We reject the model because it is not consistent with both data sets. In the next round of applying the scientific method, we would consider an alternative model such as: increased cancer rates are caused by something associated with the sites chosen for nuclear power plants.

This template may seem intimidating at first, but the example is simple enough that filling in the template is merely a matter of putting the pieces into the right pigeon-holes.

Example 2: Fetal alcohol syndrome

As little as 30 years ago, excessive alcohol was known to be a health risk to the drinker, but there was no public awareness of its possible impact on the fetus developing in a pregnant woman. In short, no one worried about it, and people were willing to assume that alcohol consumption by the mother was not a problem for the fetus. In the language of science, we would say that this public indifference was in fact an implicit model: alcohol consumption had no lasting effect on the fetus.

The first scientific studies on this topic were published in the early 1970s and demonstrated that women who drink a lot of alcohol during pregnancy have a much higher-than-average chance of producing an offspring suffering from mental retardation and various facial deformations. These data thus rejected that original model in favor of a model in which excessive alcohol consumption caused birth defects.

Later, in the 1980s, it was discovered that drinking even modest amounts of alcohol could cause the child to suffer learning disabilities and to be comparatively inept at certain physical tasks. At this point, the data supported a model in which consumption of moderate as well as excessive doses of alcohol could cause birth defects, with the dose corresponding to the degree of consumption.

Even with this progress, questions remain unanswered today, including whether drinking less than two drinks per day has any affect, and whether drinking in the first month of the pregnancy has a different affect than does drinking in the second and third months. That is, we aren't able to discriminate between models in which sporadic, light consumption of alcohol has slight, lasting effects on the fetus versus models in which such consumption has no effect. Using our template:

This template is easily extended to accommodate refinements of the model in light of the data from the 1980s.

A continual process of improvement

Science is a process, and our ideas keep changing. These changes may be merely refinements of earlier ideas, or they may be complete overhauls in our understanding. Probably the most important single feature to remember about the scientific method is that it is a means by which we can achieve progress. The scientific method is used when we are trying to improve something, whether it be to cure cancer, design a new vaccine, increase profits or build a better airplane. Each success breeds new expectations, so that there is rarely any point at which we stop the process. Improvement and progress is measured by the turnover of models: better models allow us to better achieve our goals. Figure 1.1 helps to illustrate the dynamics that underlie this progress.

Pictorial view of the scientific method, showing the dynamics involving the different elements. Starting point in any inquiry is a goal. Then one develops a model of the process that will be studied or the phenomenon that will be manipulated. From there data are gathered (or one uses data that have already been gathered). The data and model are compared in a process of evaluation, which is simply a process of deciding if the model can make sense of the data. If the model does not perform well, it is revised -- either discarded completely or modified, and the process is repeated.

Except for the goal, each element in the scientific template is subject to change, so it is best to think of the scientific method as a cyclic process, repeated over and over. (For any given goal, the other 4 elements will be changing as progress is made toward that goal.) Thus, we start with one or more models of how we think nature works. These models are compared to data (the evaluation stage), and if the model is obviously at odds with the data, it is modified or replaced by a completely new one (revision). Whether the old model is retained or rejected, the process is continued with further refinements of data and evaluation.

Although we have formally dissected only two examples according to our template, there are many examples of progress achieved this century using the scientific method. Some of these are feats of engineering, as in larger buildings, bridges, and airplanes, or better electronic appliances such as stereos, televisions, and microwave ovens. In biology, perhaps the greatest progress has been in genetics:

• 1900: rediscovery of Mendel's laws
• 1916: first proof of the chromosome theory of heredity
• 1944: demonstration that DNA was the material basis of heredity
• 1953: structure of DNA solved
• 1977: first entire sequence of a DNA genome (a bacteriophage)
• 1980s: genes identified for several inherited diseases
• 1990s: first gene therapy trials to correct genetic defects in humans

These events are only some of the more important advances; the science of genetics is filled with countless improvements of a lesser magnitude as well as many ideas overturned.

Progress is also evident in our understanding of the relationship between radiation exposure and cancer:

• 1927: discovery that X-rays cause inherited mutations in flies
• 1945: atomic bombs dropped on Japan
• 1950s: increased cancer rates observed in Japanese survivors; atmospheric testing of hydrogen bombs
• 1956: Report of BEAR (Committee on Biological Effects of Atomic Radiation)
• 1960: Report of BEAR II
• 1972: Report of BEIR I (Committee on Biological Effects of Ionizing Radiation)
• 1980: Report of BEIR III
• 1988: Report of BEIR IV
• 1990: Report of BEIR V
• 1994: Report of BEIR VI

Although we have left out the recommendation of these reports, they have generally established the criteria by which the harmful social effects of radiation should be measured and then recommended acceptable exposure levels based on various evidences. Subsequent reports have in some cases modified the recommendations of earlier reports and in other cases have broadened the awareness of possible threats (e.g., household radon was not a concern in the early reports).

It might seem that improvement stops when the scientific method has achieved perfection. That is, we should be done once we have proved a model to be true, right? No. Science does not prove models to be true and does not achieve perfection. For example, we will never know all possible health risks to the fetus of maternal alcohol consumption or know all the environmental effects of a nuclear power plant. And computers continue to improve, as do airplanes.

The point of this book is to relate the scientific method to examples in everyday life - problems not traditionally regarded as science, and problems that will affect you regardless of your chosen career. The next chapter initiates that objective.

Summary

You should conclude this chapter on the scientific method with 3 simple points:

• the scientific method has five elements (goals, models, data, evaluation, revision),
• the scientific method is cyclic,
• the scientific method is a means of achieving progress toward a chosen goal.