THE SCIENTIFIC METHOD FOR RESEARCH

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THE SCIENTIFIC METHOD FOR RESEARCH

Objectives

When you have completed this section, you should be able to

• describe the inductive and hypothetico-deductive methods of

obtaining scientific knowledge;

• describe some aspects of experimental design that help to

ensure objective and reliable results; and

• explain what is meant by hypothesis,peer reviews, fact, law, and theory in

Science.

INTRODUCTION

• Prior to the seventeenth century, Science was done in a haphazard way by a small number of isolated individuals. 

• The philosophers Francis Bacon (1561–1626) in England and René Descartes (1596–1650) in France envisioned science as a far greater, systematic enterprise with enormous possibilities for human health and welfare.

• Bacon and Descartes are credited with putting science on the path to modernity, not by discovering anything new in nature or inventing any techniques—for neither

• man was a scientist—but by inventing new habits of scientific thought.

• When we say “scientific,” we mean that such thinking is based on assumptions and methods that yield reliable, objective, testable information about nature.

•  The assumptions of science are ideas that have proven fruitful in the past—for example, the idea that natural phenomena have natural causes and nature is therefore predictable and understandable. The methods of science are highly variable.

Scientific method 

• It refers less to observational procedures than to certain habits of disciplined creativity, careful observation, logical thinking, and honest analysis of one’s observations and conclusions.

• To make such judgments depends on an appreciation of how scientists think, how they set standards for truth, and why their claims are more reliable than others.

The Inductive Method

• The inductive method, first prescribed by Bacon, is a process of making numerous observations until one feels confident in drawing generalizations and predictions from them. What we know of anatomy is a product of the inductive method. We describe the normal structure of the body based on observations of many bodies.

• This raises the issue of what is considered proof in science. We can never prove a claim beyond all possible refutation. We can, however, consider a statement as proven beyond reasonable doubt if it was arrived at by reliable methods of observation, tested and confirmed repeatedly, and not falsified by any credible observation.

• In science, all truth is tentative; there is no room for dogma. We must always be prepared to abandon yesterday’s truth if tomorrow’s facts disprove it.

The Hypothetico-Deductive Method

• Most physiological knowledge was obtained by the hypothetico-deductive method. An investigator begins by asking a question and formulating a hypothesis—an educated speculation or possible answer to the question. 

• A good hypothesis must be (1) consistent with what is already known and (2) capable of being tested and possibly falsified by evidence. 

• Falsifiability means that if we claim something is scientifically true, we must be able to specify what evidence it would take to prove it wrong. If nothing could possibly prove it wrong, then it is not scientific.

• The purpose of a hypothesis is to suggest a method for answering a question. From the hypothesis, a researcher makes a deduction, typically in the form of an “if-then” prediction: If my hypothesis on epilepsy is correct and I record the brain waves of patients during seizures, then I should observe abnormal bursts of activity. 

• A properly conducted experiment yields observations that either support a hypothesis or require the scientist to modify or abandon it, formulate a better hypothesis, and test that one. Hypothesis testing operates in cycles of conjecture and disproof until one is found that is supported by the evidence.

Experimental Design

Doing an experiment properly involves several important considerations.

•  What shall I measure and how can I measure it?

•  What effects should I watch for and which ones should I ignore? 

• How can I be sure that my results are due to the factors (variables) that I manipulate and not due to something else? 

• When working on human subjects, how can I prevent the subject’s expectations or state of mind from influencing the results?

•  Most importantly, how can I eliminate my own biases and be sure that even the most skeptical critics will have as much confidence in my conclusions as I do? 

Several elements of experimental design address these issues:

Sample size

• The number of subjects (animals or people) used in a study is the sample size. An adequate sample size controls for chance events and individual variations in response and thus enables us to place more confidence in the outcome. 

• For example, would you rather trust your health to a drug that was tested on 5 people or one tested on 5,000?

Controls

•  Biomedical experiments require comparison between treated and untreated individuals so that we can judge whether the treatment has any effect.

•  A control group consists of subjects that are as much like the treatment group as possible except with respect to the variable being tested.

•  For example, there is evidence that garlic lowers blood cholesterol levels. In one study, a group of people with high cholesterol was given 800 mg of garlic powder daily for 4 months and exhibited an average 12% reduction in cholesterol. 

• Was this a significant reduction, and was it due to the garlic? It is impossible to say without comparison to a control group of similar people who received no treatment.

•  In this study, the control group averaged only a 3% reduction in cholesterol, so garlic seems to have made a difference.

Psychosomatic effects

•  Psychosomatic effects (effects of the subject’s state of mind on his or her physiology)can have an undesirable impact on experimental results if we do not control for them.

•  In drug research, it is therefore customary to give the control group a placebo —a substance with no significant physiological effect on the body. 

• If we were testing a drug, for example, we could give the treatment group the drug and the control group identical-looking starch tablets. 

• Neither group must know which tablets it is receiving. If the two groups showed significantly different effects, we could feel confident that it did not result from a knowledge of what they were taking.

Statistical testing

•  If you tossed a coin 100 times, you would expect it to come up about 50 heads and 50 tails. If it actually came up 48:52, you would probably attribute this to random error rather than bias in the coin. 

• But what if it came up at 40:60? At what point would you begin to suspect bias?

•  This type of problem is faced routinely in research—how great a difference must there be between control and experimental groups before we feel confident that the treatment really had an effect? 

• What if a treatment group exhibited a 12% reduction in cholesterol level and the placebo group a 10% reduction? Would this be enough to conclude that the treatment was effective?

•  Scientists are well grounded in statistical tests that can be applied to the data “We can be 99.5% sure that the difference between group A and group B was due to the experimental treatment and not to random variation.”

Peer Review

• When a scientist applies for funds to support a research project or submits results for publication, the application or manuscript is submitted to peer review—a critical evaluation by other experts in that field. 

• Even after a report is published, if the results are important or unconventional, other scientists may attempt to reproduce them to see if the author was correct.

•  At every stage from planning to post publication, scientists are therefore subject to intense scrutiny by their colleagues.

•  Peer review is one mechanism for ensuring honesty, objectivity, and quality in science.

Facts, Laws, and Theories

• The most important product of scientific research is understanding how nature works—whether it be the nature of a pond to an ecologist or the nature of a liver cell to a physiologist. We express our understanding as facts, laws, and theories of nature.

• A scientific fact is information that can be independently verified by any trained person—for example, the fact that an iron deficiency leads to anemia. 

• A law of nature is a generalization about the predictable ways in which matter and energy behave. It is the result of inductive reasoning based on repeated, confirmed observations.

• A theory is an explanatory statement, or set of statements, derived from facts, laws, and confirmed hypotheses. 

• Some theories have names, such as the cell theory, the fluid-mosaic theory of cell membranes, and the sliding filament theory of muscle contraction.

• Law and theory mean something different in science than they do to most people.

•  In common usage, a law is a rule created and enforced by people; we must obey it or risk a penalty. 

• A law of nature, however, is a description; laws do not govern the universe, they describe it.

• The concepts of gravity and electrons are theories, too, but this does not mean they are merely speculations.

CONCLUSION 

SCIENTIFIC METHOD ARE THE SET OF RULES AND REGULATIONS THAT MUST BE OBEYED ON SET OF POPULATIONS TO TEST A COLLECTION OF VARIABLES/HYPOTHESIS TO GET A EXPERIMENTED/PROVEN DATA. 

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