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Studying Cells Tutorial

The Scientific Method

What is it?
The scientific method is the experimental testing of a hypothesis formulated after the systematic, objective collection of data. A scientist who studies our immune system phrased this idea very well:

 

I now appreciate how much I learn by being wrong. I can change my mind when confronted with a rational argument, without the need to have the change appear to be purely semantic or to hope it will pass unnoticed. What must it be like to be a priest, general, bureaucrat, lawyer, medicine person, or politician who is never permitted to be wrong? No wonder they learn so slowly. I am grateful to be in a profession where the realization of being wrong is equivalent to an increase in knowledge.

-Melvin Cohn. Annual Review of Immunology 12, 2 (1994)
The scientific method is often divided into steps. This is helpful for putting the method into context, but keep in mind that the key element of the scientific method is testing the hypothesis. In other words, can you prove that you are wrong?
  1. Observe the situation
  2. Ask a question
  3. Turn that question into a testable hypothesis
  4. Predict the outcome of your experiment
  5. Perform your experiment
  6. Analyze the results
  7. Evaluate your hypothesis
Evaluating science
Mistakes made in applying the scientific method to real-world problems can result in unsupported, or even incorrect, conclusions. An example of a scientific conclusions based on insufficient scientific method recently occurred in the field of breast cancer research.
Breast cancer is caused when normal cells change and produce a tumor. In a study published in the New England Journal of Medicine (336, 1269 (1997)), scientists from Norway studied the incidence of breast cancer in 25,624 women.

Participants gave details about their height, weight, diets, and exercise habits. The results showed an over all reduction of breast cancer by 37% for women who exercise regularly. Women who are lean and exercise at least 4 hrs per week showed the lowest incidence.

Micro photo of breast cancer tissue
Image courtesy of WebPath
Many newspapers picked up on the data with headlines stating that exercise prevents cancer, but an editorial in the same journal by Dr. Anne McTiernan put the results in proper perspective (ibid. p. 1311). She points out that women who exercise regularly have higher levels of education and income, smoke less, drink less alcohol, and consume fewer calories and less fat. She states that establishing a casual pathway between reduced breast cancer and physical activity will require exploration for biologic mechanisms and confirmation with clinical experiments. Her final conclusion states the situation very well.


Should a woman exercise and will it prevent breast cancer? I recommend a resounding YES to the first question. Regular physical activity in women reduces overall mortality and the incidence of coronary heart disease, diabetes mellitus, stroke, osteoporosis, obesity, and disability, and it also lessens the impact of arthritis and cognitive decline. With respect to whether exercise reduces the risk of breast cancer, too many questions remain for women and their doctors to make informed decisions on whether, how and how much to exercise.

-Dr. Anne McTiernan, New England Journal of Medicine (336, 1311 (1997))

This example illustrates many of the problems associated with the science of biology and medicine.

Introduction | Size & Biology

Vocabulary

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