The Scientific Method

The Scientific method is used by researchers to study nature in a rational, and logical manner.  The scientific method protocol consists of a series of steps, which can vary between scientific disciplines.  Ultimately, science is not based on proof but on disproof.  If we conduct an experiment to test our hypothesis and the results support our hypothesis, we state that the hypothesis is supported.  If the experiment demonstrates that our hypothesis is not correct, then we state that the hypothesis was not supported.  The scientific method is conducted according to the following steps:

1. Making observations
2. Developing a hypothesis
3. Conducting experiments
4. Analyzing experimental data
5. Drawing conclusions
6. Supporting or not supporting hypothesis
7. Revising hypothesis based on new data

Making Observations:  An observation is generally expressed as a question.

Developing a hypothesis:  A hypothesis is a proposed solution to our observations and question.  We usually test only one hypothesis at a time.  We create a “null hypothesis” as a competing hypothesis that claims our proposed solution is false.  If it is false, the experimental data will not support our hypothesis and we must reject it.  However, if the data do support our hypothesis, we must understand that this same set of data might support other hypotheses as well.  Support of a hypothesis does NOT prove it is true.  The experimental data may only be a correlation of the data and the hypothesis and not necessarily mean causation. All hypothesis-driven investigations must be scientifically testable by controlled experiments.

Conducting experiments:  After a testable experiment is formulated along with a “null” hypothesis, experiments are designed to test this hypothesis.  To design scientifically valid experiments, one must include a “control” group that is not being exposed to the variable that is being tested.  The control group does not receive the questioned treatment but is similar in all respects to the group receiving the treatment.  The test group generally is tested for its reaction to a single variable.

Analyzing Experimental data:  Data is gathered during the experiment and subjected to statistical testing for relevance.  Experimental data should always be repeated to test for validity.  Data that cannot be easily replicated is suspect.

Drawing conclusions:  Conclusions are then drawn from the results of the data collection.  Sometimes the hypothesis may be supported and other times, the hypothesis may not be supported.  Statistical significance is important when determining whether the data supports the hypothesis.

Difference between a hypothesis and a theory:  A hypothesis is a proposed, testable question providing a solution to a problem.  It is usually very specific in nature.  In contrast, a theory is an encompassing established explanation that accounts for all known facts and phenomena.  A theory is a statement that has never been disproven.

NOTE:  All hypotheses and theories can be amended and changed if new evidence arises.

Most forms of scientific study combine both descriptive and hypothesis-driven science.  Often small studies (especially in human medicine) will be descriptive in nature.  Demonstrating a specific trait or condition in a population of subjects.  A number of descriptive studies are put together to form the basis of a hypothesis.  Once a hypothesis is developed, experiments can be designed to specifically test the question proposed and the statistical significance of the results.

Activity (8 points):

You will be researching the following topic: Pulse rate in Men versus Women

The experiment is: You have a group of 20 men and 20 women, ages 30-40 yrs of age.  All of your subjects are going to run in place for 15 minutes and then you are going to check their pulses after they run.

Answer the following points with the above experiment  (1 point each):

1. State your hypothesis-A testable statement-be specific
2. Identify your control group (group with no testing
3. Identify your experimental group (group testing your hypothesis)
4. What results would you need to obtain to support your hypothesis?
5. What results would need to obtain to disprove your hypothesis?
6. How would you change the hypothesis if it was disproven? State your new hypothesis
7. State your new control group.
8. State your new experimental group.