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A primary source in the sciences is usually
a report on the results of an experiment by the person or
group who performed it.
The scientist reports the results of his or her own research.
It is not a comment on someone else’s research, although
the scientist may refer to someone else’s work in the
body of the paper to illustrate the points he/she is trying
to prove or disprove. Most scientific journals that are peer-reviewed
are likely to contain primary literature. Peer-review means that a panel of experts will review all articles submitted
for publication before they are accepted for the journal.
In a primary research article/experiment, you will typically see many or all of the following elements clearly laid out:
- An abstract/summary of the research about to be presented
- Author’s credentials
- Introduction with thesis statement
- A review of other literature pertaining to the experiment
- Methods used to conduct the experiment
- Materials and Equipment used in the experiment
- Results of the experiment (data) - may include tables, charts, graphs, figures, photographs
- Discussion of the results
The presence of these components indicate that the author
is presenting new data and ideas.
Here is an example of a primary science article. The journal title itself hints about the nature of the article: "clinical investigation. The abstract also provides clues (highlighted in red below):
- “...remains to be verified”
- “we detected...”
- hard-core scientific terminology
- brief report on methods: "we compared..."
- brief statement of conclusion: "..this model can be used..."
vivo blood flow abnormalities in the transgenic knockout sickle
Author(s): Embury SH, Mohandas N, Paszty C, Cooper P, Cheung ATW
Source: JOURNAL OF CLINICAL INVESTIGATION 103 (6): 915-920 MAR 1999
Document Type: Article
Abstract: The accepted importance of circulatory impairment to sickle cell anemia remains to be verified by in vivo experimentation. Intravital microscopy studies of blood flow in patients are limited to circulations that can be viewed noninvasively and are restricted from deliberate perturbations of the circulation. Further knowledge of sickle blood flow abnormalities has awaited an animal model of human sickle cell disease. We compared blood flow in the mucosal-intestinal microvessels of normal mice with that in transgenic knockout sickle cell mice that have erythrocytes containing only human hemoglobin S and that exhibit a degree of hemolytic anemia and pathological complications similar to the human disease. In sickle cell mice, in addition to seeing blood flow abnormalities such as sludging in all microvessels, we detected decreased blood flow velocity in venules of all diameters. Flow responses to hyperoxia in both normal and sickle cell mice were dramatic, but opposite: Hyperoxia promptly slowed or halted flow in normal mice but markedly enhanced flow in sickle cell mice. Intravital microscopic studies of this murine model provide important insights into sickle cell blood flow abnormalities and suggest that this model can be used to evaluate the causes of abnormal flow and new approaches to therapy of sickle cell disease.
Secondary sources in the sciences are often referred to as REVIEW articles. Review articles summarize, interpret, or analyze the findings of a scientist or group of scientists studying the same thing. They may discuss the ways in which various researchers' work is related or consider the implications of the research. They look more like traditional journal articles, not laid out in a linear way. These are the types of articles you might find in Discover magazine, although you will certainly find them in higher-level scholarly journals as well.
You should always consult the primary article under discussion when using secondary sources as support.
Here is an example of a secondary scientific article. The title and abstract provide clues as to the nature of the article:
- the word “history” is in the article title
- relative lack of scientific terminology in the abstract
- "...this article describes the research path..."
of innovation: a history of the first effective treatment
for sickle cell anemia.
Williams VL. PERSPECTIVES IN BIOLOGY AND MEDICINE. Autumn 2004.Vol.47, Iss. 4; pg. 552.
Document type: Historical Article
Source type: Periodical
Abstract: The promise of molecular medicine is the prevention and treatment of illness. Understanding the mechanism of the disease should allow one to "fix" it. For sickle cell anemia, however, knowledge of the biochemical basis of the disease was only partly responsible for finding a means of treating the disease--of equal value were hypotheses and conclusions generated from clinical observations. This article describes the research path that led to the first effective treatment for sickle cell anemia, hydroxy-urea. Rather than exemplifying the "bench-to-bedside" model commonly used to describe the process of therapeutic innovation, this history of this research reveals that the critical advances for the development of treatment came not from basic research, but instead from clinical and patient-oriented research. Given that the linear approach is the prevailing paradigm of therapeutic innovation, this history is important because it indicates the inadequacy of this approach for a relatively straightforward single-gene mutation disease such as sickle cell anemia and suggests the need for multiple models of innovation for more complex diseases. Thus, this article questions the expectations of molecular medicine and the dominance of a linear model of therapeutic innovation, which often excludes or subordinates other models of developing treatments.
Neither primary nor secondary articles are easy to isolate during database searching. Most databases do not identify primary articles as such.
Review articles may be identified as such or as "historical" articles and can sometimes be isolated in scientific databases by selecting the "review" article (or similar) option on advanced search screens. However, because not all review articles are identified, many important articles can be missed using this method.