Scientific Methods

Biology I

Many Methods• There is no unique "Scientific Method."

Scientists use many methods of investigation and reasoning, and most of them are also used in other fields of human endeavor.

The Scientific Methodby Donald E. Simanek

• Too often the "scientific method" is presented in schools and textbooks as a "recipe" for doing science, with numbered steps even! That's misleading.

• Science progresses through trial and error, mostly error. Every new theory or law must be skeptically and rigorously tested before acceptance.

Excerpts from his Internet article http://www.lhup.edu/~DSIMANEK/scimeth.htm

Scientific Method

• The most reliable means to ensure that experiments produce reliable information in response to a specific question.

• The steps taken to answer a specific question.

Some Steps that may be used in scientific research

• Observations• Form questions• Make hypotheses• Design an experiment• Analyze results • Make conclusions

• Scientific method is based on the principle of cause and effect: You get a fever because you are sick; the sky looks blue because of the interaction of light and matter in the atmosphere.

• Not all of these common phenomena are completely understood, and still others cannot be explained at all.

Observation

• So what does a scientist do when he or she uses the scientific method in the exploration of the unknown?

• First of all, the scientist tries to learn as much about a subject as time - or funding - allows. This requires a thorough study of the available literature, gathering information and data from a variety of sources, discussions with colleagues, and a lot of thinking.

Hypotheses

• After data has been collected and analyzed, the scientist formulates an hypothesis. It may be a short leap of logic, or an intuitive leap of faith.

What is a Hypothesis?

A hypothesis is

• A logical but unproven explanation for a given set of facts.

• Developed through observations or previous experiments

• Usually an If/then statement• Ex. If the plant is not watered, then it will die.

Experiment

• The researcher then designs experiments to provide evidence in support of the hypothesis.

• The scientist must gather substantial amounts of data. Analysis of the data will either suggest the validity of the hypothesis or encourage revision.

• Once revised and retested, the hypothesis must withstand the scrutiny of other scientists as well. They may repeat the experiment to retest the validity of the hypothesis, along with the validity of the methods used to test the hypothesis.

Experiments

• Tests a hypothesis by collecting information under controlled conditions.

There are two groups in an experiment• Control group – all conditions kept normal• Experimental group (test group) – all

conditions kept the same as the control except for the single condition being tested.

Variables

• Independent variable – experimental variable- the thing changed (tested) in the experiment.

• Dependent Variable – changes in this condition depends on changes in the independent variable.

The dependent variable depends on the independent variable.

Data

• Quantitative – numerical counts or measurements

• Scientific measurements are always metric

• Reported in graphs or tables

• Qualitative (descriptive) – written descriptions.

Theory

• An idea, model, or explanation that has been rigorously tested, analyzed, and accepted by the scientific community is referred to as a theory - a term used, perhaps, because most scientists believe nothing can ever be proved absolutely true.

• The theory will continue to be an accepted explanation unless new information is uncovered - information that the scientific community agrees disproves the previous explanation. This continuous scrutiny is essential to the credibility and progress of scientific research.

Designing Experiments

The PurposeThe purpose clearly states the phenomenon or question you plan to investigate.

• Your purpose should guide your experimentation and help keep you on track.

Hypotheses

• The next step is to formulate hypotheses.

• An hypothesis is your informed prediction about the outcome of your research.

Variables

• You should clearly state the variables in your experiment.

These include dependent, independent as well as controlled variables.

Procedure

• Raw data by itself is meaningless unless people know how it was collected.

• You should describe the method you followed to obtain your data as well as the materials and equipment used so that anyone could reproduce your experiment at a later date.

Results/Data

• This includes all the data you collect from your procedure. All data, whether it fits with what you expected or not, must be recorded.

• Your results should be presented in the clearest way possible. Quite often this will include graphs and charts to show trends and relationships.

Conclusions

• Is an explanation for the data collected.

• The conclusion must be based on the results of your experiment and should explain how you reached that conclusion.

• It should also include whether or not your data agrees with your hypothesis

Communicate

• The last step is to communicate the results with others.

• Scientists publish their research in journals – The New England Journal of Medicine.

Resources

• http://www.dharma-haven.org/science/myth-of-scientific-method.htm

• http://www.accessexcellence.org/RC/AB/BC/Elegant_Experiments.html