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Health Sciences and Human Nutriton and Physiology Research: Evaluating Research

Evaluating Research

What's in a scholarly journal?

Not everything in a scholarly journal is peer reviewed. Here are some source types that can be found in a scholarly journal:


These are opinion pieces. Although they tend to be informed opinions from experts in the field, these pieces usually aren't subject to peer review. 


Theory pieces explore the underpinnings of care and health science. These pieces may or may not be subject to peer review depending on the journal, and they tend to not include an actual study or experiment. 


Research articles are usually the evidence based practice and, in a peer reviewed journal, are subject to peer review. 

Continuing Education

These are pieces, usually for nurses, that discuss studies or research on new care standards, interventions, or practices. They may summarize or include a study or studies, but usually have a quiz and different formatting than a standard scholarly article. 

Parts of an Article


The abstract is a brief summary of the article. 


The introduction introduces the problem, question, or main idea and the bigger context of the paper.

Literature Review

The literature review discusses what other studies or information already exists around this topic.


The methodology details how the study was conducted, who was in the sample, how the sample was taken, and what analysis was used to reach the results.


The results are usually tables or statements about what the study uncovered. 


The discussion is where the authors talk about what the results indicate or mean in the context of their research question.

Conclusion (and Limitations)

The conclusion wraps up the paper, suggests future research directions, and typically addresses any limitations of their research. For instance, how well does the sample represent reality? How broadly can we apply these results? What could have affected the outcomes of this study?

Questions to Ask When Evaluating a Study

Who is represented in the sample and who is missing? 

Think critically about the representation of race, gender, disability, and economic status in human studies. 

How was this sample collected? 

Often samples can be self-selecting or inherently skewed. For instance, if you conduct interviews on diet in a pricey health foods store, you're going to get a very different sample than you might in a different location. Your results are going to be skewed by the population included. 

Does the methodology make sense for the question being asked? 

You get the data you ask for. Do the tools used in this study provide data that would actually answer the research question?

Do the conclusions seem reasonable based on the results? 

If 55% of students said they liked this libguide, would it be okay if I said a vast majority of students liked it? No. Check that the conclusions don't overstate the results. 

Do the limitations of the study invalidate the results?

Every study has limitations, but consider them critically and make sure you address them when you talk about conclusions from an article. 

What is evidence based practice?

Evidence based practice refers to articles where a study has been conducted. Unlike articles that are theory or commentary, an evidence based article has a population, an intervention (or variable of interest), and gathers and interprets the results to offer a recommendation. 

The Pyramid of Evidence

When discussing "evidence based practice" and articles that are "evidence based," there are several common models that put types of studies in a pyramid according to how much evidence they provide. For example a case study with one subject may not provide as much evidence as a randomized controlled trial with 400 participants. The amount of evidence is determined largely by the number of participants, but also the presence of a control group. 

Here's the one pyramid model of evidence (CC-0): 

An EBP pyramid. From top to bottom, clinical practice guidelines, meta-analysis, randomized controlled trial, cohort studies, case control studies, narrative reviews and expert opinions, animal and labratory studies with no humans involved.


A few things to keep in mind:

  • depending on your question, a case study or small qualitative study may be better than a large quantitative study
  • if a large sample lacks diversity or doesn't cover the population you're interested in, its results could still have limited applicability for your research
  • the pyramid here only represents one way of evaluating evidence. It is neither foolproof, nor absolute. Be sure to consider your assignment or research question requirements.

Conflict of Interest

Why do papers include a "conflict of interest" statement? 

A conflict of interest is a significant financial interest in the results of research. For example: a study concludes that women are gaining weight because they're doing less housework, but the study was funded by Coca Cola (that's a real thing). In considering the article's conclusions, it's important to know who has a stake in the outcomes and who might have influenced those outcomes.

Most journals require authors to disclose any information that readers ought to know about possible conflicts of interest, like who funded the research, if the researchers are employed by the companies involved, if the researchers have stock or other financial interests in the products tested. 

Retraction Watch

Why do articles get retracted? 

Studies can be retracted for a number of reasons:

  • Included information that compromises participants' confidentiality.
  • Undisclosed conflict of interest.
  • Faulty data or faulty methods.
  • Misrepresented or intentionally skewed results.
  • And more.

If after publication, someone discovers a paper contains mistakes or lies, the paper can be retracted. Then a journal will issue a retraction notice, and the article itself will be clearly labeled. 

Retraction Watch

Retraction Watch can be an interesting site for learning about research misconduct and for discovering retracted research, if you're specifically looking for it.