The Scientific Method

Image Copyright © Sidney Harris. Reprinted with Permission.

The goal of any scientific study is to learn about, describe and/or explain some aspect of the real world. In the biological sciences, for example, we might be interested in determining the number of organisms of a given species that inhabit a given area, or we might be interested in the effect of some variable or treatment on a physiological process. Whatever the specific objective of the study, the validity of the study depends on the proper application of the scientific method.

The scientific method is a method of investigation and inquiry based on objective observation, experimentation and the accumulation of measurable evidence. The general process consists of four basic steps: posing a question, formulating a scientific hypothesis, making scientific predictions and designing and executing the scientific study to determine whether the hypothesis is correct.

1. Posing a question. The first step in beginning any scientific inquiry is the development of a question about the real world. The question is completely up to the individual initiating the inquiry, but must always be based on objective observations of the real world. Often times the question is formulated after evaluating the results of previous scientific studies and attempts to continue a line of questioning developed by other scientists.

2. Formulating a Scientific Hypothesis Once the question is posed, a hypothesis is formulated. A hypothesis is basically a conjecture that attempts to explain the phenomenon addressed in the question. A scientific hypothesis is a hypothesis that can be tested using the scientific method. If the hypothesis is not testable, it is not a valid scientific hypothesis.

Do not confuse a scientific hypothesis with a scientific theory. A hypothesis sets the stage for and is the foundation for a scientific inquiry. A scientific theory is an explanation of a real world phenomenon based on the observations and experimentation.

Every scientific study also has a null hypothesis - the conjecture that the stated scientific hypothesis is false. If the results of a scientific study support the scientific hypothesis, the null hypothesis is rejected.

3. Making Scientific Predictions. With the hypothesis stated, scientific predictions are made. A scientific prediction is a specific, sometimes quantitative, forecast of expected results when conditions are applied to the phenomenon under investigation if the hypothesis is true.

4. Designing and Executing the Scientific Test of the Hypothesis. Finally, a scientific test is designed to answer the question and determine whether the real world behaves according to the stated hypothesis. The test is a properly-designed process of accumulating evidence (data) through observation or controlled experimentation (see Principles of Experimental Design below). There are two basic types of scientific tests. An experiment imposes a treatment or experimental condition on a group of objects or subjects to observe the response. An observational study imposes no experimental treatment. It involves collecting and analyzing data under existing native conditions.

The validity of the scientific study is directly affected by its design. Therefore, the design of the study must be thoroughly planned before any experimentation takes place. Planning should be done with the hypothesis and the possible type of statistical analysis that will be performed in mind.

Once designed, the scientific study is executed. The validity of the scientific study is directly affected by its execution. Therefore, careful execution of the study is paramount.

The data accumulated during the study must be carefully recorded and objectively analyzed using appropriate statistical analysis. The results of the analysis are used to draw conclusion that either supporting or reject the null hypothesis and, in that way, answer, to some degree, the question initially asked.

An important aspect of the test is its documentation. Scientists must properly record the testís methodology, data and the results of the data analysis. The record allows peer review of the test and proper replication of the test if deemed necessary.


  • Chalmers, A. What is this thing called science? Queensland University Press and Open University Press, 1976.
  • Franklin, J. What Science Knows: And How It Knows It, New York: Encounter Books, 2009.
  • Gauch, H.G., Jr. Scientific Method in Practice, Cambridge University Press, 2003.
  • Jarrad, RD. Scientific Methods
  • Latour, B. Science in Action, How to Follow Scientists and Engineers through Society, Harvard University Press, Cambridge, MA, 1987.
  • Popper, K R. The Logic of Scientific Discovery, Routledge, 1959.
  • Schafersman S.D. Scientific Thinking and the Scientific Method,
  • Wilson, E. Bright. An Introduction to Scientific Research. McGraw-Hill, 1952.
  • Wikipedia. Scientific method (
  • Wikipedia. Outline of scientific method (
  • Wikipedia. Prediction (
  • Wikipedia. Hypothesis. (

CellBiologyOLM is authored by Stephen Gallik, Ph. D.| Copyright © 2011 by Stephen Gallik, Ph. D. | Licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License