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Nursing Students' Guide to Evidence Based Research: Reading and Evaluating Research

Resources for Nursing Students

Scientific Method - A Quick Review

Scientific method forms the basis of clinical research, as well as many other forms of research.

This infographic lists the basic stages of the scientific method: 1. Ask a Question; 2. Construct a Hypothesis; 3. Test Hypothesis; 4. Analyze Results; 5. Draw Conclusions

In practice, of course, it's more complicated than the diagram above implies. Professional scientists start out with a question that's based on what they know about their subject. But research moves fast in science, so they need to review what research other scientists have done before they move ahead. Then they need to design their study carefully. When they have concluded their research, they need to publish it to share with other scientists. As the research on this topic cumulates, the people who study it start to create systematic theories to explain the findings. The infographic below illustrates this process as a cycle.

The infographic shows six small circles arranged in a larger circle. In the center is the image of a scientist. The cycle begins with step 1, and arrows indicate the progress from one step to another. Each circle represents one of six steps, and contains text. As the circle closes between step six and step 1, the process continues into a new cycle. Here is the text from each of the circles. Step 1: Literature Review: The scientist conducts a literature review, reading what has been published in major scientific journals on the subject of interest. Step 2. Testable hypothesis, operationally designed: the scientist makes a testable hypothesis, or a specific prediction about how one factor, or variable, is related to another. To be scientifically testable, the variables must be operationally defined – that is, stated precisely and in measurable terms. Step 3. Research design: The scientist chooses the best research design to test the hypothesis and collect the data. She might choose naturalistic design, case studies, surveys, experiments, or other methods. Step 4. Statistical Analysis: The scientist performs statistical analyses on the new data to determine whether the findings support or reject here hypothesis. This allows her to organize, summarize, and interpret the numerical data. Step 5. The scientist writes up the study and its results, and submits it to a peer-reviewed journal. [Peer reviewed journals ask other scientists to evaluate the submitted material.] On the basis of these peer reviews, the study may then be accepted for publication. Step 6. Theory: After one or more studies on a subject, researchers generally advance a theory to explain their results. This theory then leads to new (possibly different) hypotheses and new methods of inquiry.

Source: Lecture Overview Introducing Psychology Origins of Psychology The Science of Psychology Research Methods Tools for Student Success © John Wiley & Sons.

Building Knowledge:

If a question or problem is interesting or urgent, more scientists will produce studies that explore the topic.

Next Stage: Scientists create more studies. These studies may try to replicate the results of the first, or to test the conclusions on a bigger, or more diverse set of subjects, or under different circumstances. As these studies are published, more knowledge about the topic is generated.

Concensus: When a growing number of studies confirms and expands the legitimacy of the original conclusions (or modifies them), and scientists agree that the knowledge gained is valid, they are said to have achieved consensus. In nursing, this leads to standards and best practices.

Reading Scientific Research

Reading research articles is different from reading light fiction, or even a textbook. Check out the resources below for help learning to read and understand clinical research articles and other scholarly literature.

A Crash Course in Statistics

To read and understand clinical research, you need to understand some basic concepts in statistics. Here are some resources to help you learn to read and understand the statistics you encounter when you read clinical studies.

Research Design and Quality of Evidence

From this pyramid infographic, you can see how research studies in health care change and grow more rigorous and authoritative over time, and the evidence builds and gains in quality. This does not mean that the early studies were badly done - what we are assessing here is the quality and quantity of the evidence that can help guide practice. Obviously, the early studies are a necessary foundation. Some versions of this pyramid insert another layer at the second level from the bottom, showing the role of animal studies and modeling in the development of a body of clinical evidence.

The infographic shows a pyramid constructed of 9 steps. Each level represents a stage in the development of knowledge about a medical topic. At each stage, the number of studies gets smaller, but the weight and value of the evidence increases. Here are the steps: Step 1: Background information, expert opinions, non-EBM guidelines [this is a pre-research stage]; Step 2: individual case reports; Step 3: case series or studies; Step 4: cohort studies [steps 2-4 are observational, or descriptive studies]. Step 5: non-randomized controlled trials; step 6: randomized controlled trials [steps 5 & 6 are experimental studies]. Step 7: critically appraised literature, evidence-based practice guidelines; Step 8: systematic reviews; Step 9: meta-analyses [steps 7-9 represent critical appraisal of the literature residing in the lower levels of the pyramid]. The arrow running up one side of the pyramid from the base to the apex shows how the value of the evidence increases, first as the number of subjects and the rigor of the studies increases, then as the medical community synthesizes and critically examines how these studies fit together to form a body of knowledge.

Source Evidence-Based Medicine: Resources by Levels of Evidence, Central Michigan University Libraries