2.9: Summary

The scientific method is a formal way to make scientific investigations. Scientists state their hypothesis, do controlled studies, then report their results and conclusions in scientific journals and meetings. Scientists throughout the world can then examine, discuss, and verify the bits and pieces of new information before adding it to the body of scientific knowledge. This process of verification is very important because each bit of new information serves as a stepping stone for further studies.

Comparison groups should be as similar as possible, except for the variable being tested. The “gold standard” in human studies is the prospective, randomized, double-blind, placebo-controlled study, e.g., the study of aspirin in the prevention of heart attacks:

Prospective: Heart attacks that occur after the start of the study are compared in those randomly assigned to the aspirin and placebo groups. (In a retrospective study, they would have been divided into those who have had a heart attack and those who haven’t, and their past use of aspirin compared.)

Randomized: Subjects randomly assigned to groups so that the aspirin and the placebo groups start off as similar as possible. This makes it more likely that any differences between the two groups will be due to the aspirin. Significantly more heart attacks occurred in the placebo group, and it was concluded that aspirin helped prevent heart attacks.

Double‑blind: Neither the subjects nor the investigators actively involved in the study know who’s getting the aspirin and who’s getting the placebo. A placebo is a substance or procedure used to control for psychological and peripheral effects that can be powerful. Not knowing who is in which group controls for unconscious bias in subjects and investigators alike. If there’s a question of whether someone actually had a mild heart attack, unconscious bias could play a role in deciding.

It’s important to note other features of a study. Although the aspirin study was prospective, randomized, double-blind, and placebo- controlled, the subjects—a selective sample of male physicians—certainly weren’t representative of the entire U.S. population. Furthermore, those who were at risk of being adversely affected by aspirin were excluded from the study.

The rapid advances in medical research and treatment wouldn’t have been possible without the use of lab animals. Rats and mice comprise about 95% of research animals. Their main advantages in research are that their environment can be precisely controlled, and they are physiologically similar to humans, can be bred to be genetically similar and with certain susceptibilities to diseases, have a short life span, and are relatively inexpensive.

When a substance (aspirin, vaccine, etc.) has been shown to be safe and effective in animal studies, it must be shown to be safe and effective in clinical trials (human studies) before it’s approved for use in the general population. Phase I clinical trials test for safety in a small group of people. Phase II trials test for effectiveness in a larger group. Phase III trials test for both safety and effectiveness in a much larger group. (Notably, dietary supplements don’t have to undergo such testing. They don’t have to be shown to be safe or effective before being sold.)

Once a study is completed, the data are evaluated statistically and by other scientists. A significant finding, by definition, means that the likelihood that the finding was due to chance alone was calculated to be less than 5 in 100 (probability = <0.05).

When you hear about the results of various studies, especially if they sound a bit offbeat, question such details as whether the study controlled for bias, who the subjects were, and whether it showed a link or a cause-and-effect relationship.

Alternative medicine lies outside of the science-based methods traditionally taught in medical schools (conventional medicine). Most people using alternative medicine use it in addition to conventional medicine (complementary medicine), or coordinated with conventional medicine (integrative medicine).

In searching for reliable health and biomed information, .gov websites as a group are reliable sources. They don’t advertise or sell products, are continually updated by experts—and are paid for by us taxpayers.