The Scientific Method
The scientific method is composed of several steps. We haveoutlined these steps below.
We note that not all biologists will follow this formatprecisely or in this order but most
researchers go through these steps during the course of theirresearch.
1) Search for information and makingobservations. (Library, Internet)
A biologist usually begins a research project with a searchthrough the biological literature. They
should be familiar with all articles relevant to theirresearch. The purpose of a literature search is to
find out what is known about a given subject. If you know whatis known then you also know
what is unknown. The area that is unknown iswhere biologists makes new contributions to
their field of study. Support or rejection of earlier ideas isanother ongoing part of biological research.
The development of new technologies often provides biologistswith new tools to test older ideas.
In both cases, a review of the literature is necessary.
2) Asking questions.
What Questions?
What is the structure of the DNA molecule (Watson and Crick1953)? Previous studies of DNA
and proteins showed that DNA was the source of the geneticcode. However, the structure of
the DNA molecule remained unknown until Watson and Crick(1953) first described the
shape of the double-helix.
What are the symptoms or indicators of humanimmunodeficiency virus (HIV) infection
(Widi-Wirski et al. 1988)? Ever since the discovery ofHIV in the late 1970's, a consensus
on a concise description of the symptoms used to diagnose HIVinfection has been lacking
because of the latency of the onset of the disease, theclinical spectrum of symptoms vary
across the world and expensive serological tests available indeveloped nations are unavailable
in third world countries. Diagnosis of this deadly diseaserequires an accurate description of
the symptoms that define a patient with HIV. Widi-Wirski etal. (1988) asked questions about
a reliable clinical definition for HIV infection that can beapplied throughout the world.
They discuss different clinical definitions used in theliterature.
What are current population trends in species of songbirdsthat breed in North America
(Sauer and Droege 1992)? Each year billions ofsongbirds migrate from their wintering grounds
in the tropics to North America. They establish nestingterritories and produce offspring during
the summer. Then, they return to the tropics to spend thewinter. If population ecologists want
to know something about the health of populations of thesespecies they would ask questions
about population trends. Sauer and Droege (1992) askedquestions about population trends in
100 species of neotropical migrants on their breeding groundsin North America. They found
that from 1978 - 1988, a majority of species experiencedpopulation declines.
How Questions
How are molecules arranged that would cause the doublehelix configuration of DNA?
Watson and Crick (1953) discovered how molecules comprisingthe two strands of
DNA are arranged and how nitrogenous bases hold the two DNAstrands together with hydrogen bonds.
How does HIV cause AIDS? After biologists discoveredHIV they needed to know
how it caused AIDS. Several investigators (Weiss 1993, Nowakand McMichael 1995)
asked how HIV affects the body and causes AIDS. This lead tothe discovery of how
HIV attacks the lymphocytes and destroys the body's immunesystem.
How has the environment caused changes in songbirdpopulations in the western
hemisphere? When ornithologists observed decliningpopulations of songbirds they
began to ask questions about how changes in the environmentcould be causing population
declines. Terborgh (1992) has reviewed several hypotheses thatmight explain these
declines including habitat fragmentation due to humandevelopment on the breeding grounds,
deforestation on the wintering grounds in the tropics,increased predation pressure by
avian nest predators (e.g., feral cat, Opossum and Raccoon),pollution, an abundance of brood parasites, and insecticides.
3) Developing testable hypotheses.
4) Test the hypothesis. Use El Nino as anexample of how climate may affect fish and seabird populations.
Hypothesis 1: If El Nino's warming is causing declines inseabird
populations,
Prediction: 1) then perturbations in oceanographicmeasurements
(e.g., temperature, salinity) of the marine ecosystem
should be temporary and followed by a recovery
until the next El Nino event,
Prediction: 2) then populations of prey species of fish willdecline in
response to these changes during El Nino years
but will recover after each El Nino event,
Prediction: 3) then seabird predators will be unable to breedbecause
they can not feed fish to their young during El Nino
years,
Prediction: 4) then after an El Nino event, seabirdpopulations will
approach their normal population sizes until the
next El Nino event.
Hypothesis 2: If overfishing is causing declines in seabirdpopulations,
Prediction: 1) then fish populations will exhibit a continuous
decline and will not recover after an El Nino
event,
Prediction: 2) then large numbers of seabirds will be unable
to breed because they can not feed fish to their young duringEl Nino and normal weather years,
Prediction: 3) then seabird populations of will exhibit acontinuous
decline that parallels a continuous decline in prey
species of fish,
Prediction: 4) then seabird populations will not recover totheir
average population sizes after an El Nino event.
5) Collect data.
6) Analyze data.
7) Interpret the results of the analysis.
8) Answer the biological question.
9) Present the results of the research.
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Copyright © 2001 Jay Pitocchelli. All rights reserved. The contents of this page are the intellectual property of Dr. Jay Pitocchelli for distribution to students enrolled in Biostatistics BI 45 at Saint Anselm College. These pages may not be copied, photocopied, reproduced, translated, or published in any electronic or machine-readable form in whole or in part without prior written approval of Jay Pitocchelli. Students enrolled in Biostatistics BI 45 at Saint Anselm College have permission to print this material for their lecture notes.