When looking for articles in journals, it is important to keep in mind that there are many types of articles. They can serve different purposes and therefore compliment your research and writing in different ways.
You can use this chart to help you decide what type of article is best for your research needs. This chart is not exhaustive and does not include every type of article, but some of the most common types.
| Article Type | Definition | Advantages/Disadvantages |
|---|---|---|
|
Systematic Reviews |
Systematic reviews focus on a clinical topic and answer a specific question. An extensive literature search is conducted to identify studies with sound methodology. The studies are reviewed, assessed for quality, and the results summarized according to the predetermined criteria of the review question. | Systematic reviews are considered more reliable and accurate than individual studies. They are considered a highly evidence-based resource. However, they tend be very long and can take some time to read. |
| Meta-Analysis |
A meta analysis is done using a method for statistically gathering quantitative studies to develop a single conclusion that has great statistical power |
A meta analysis will provide a conclusion that is statistically stronger than any single study because of its use of increased numbers of subjects, diversity of subjects or accumulated effects and results. However, some authors will have a difficult time identifying appropriate studies since not all studies provide adequate data for inclusion and analysis. A meta analysis also requires advanced statistical techniques. |
| Critically Appraised Topics | CAT's are a brief evidence based critical appraisal of one or two relevant studies to answer a clinical question. | A CAT provides a short and brief review. However, it is a less rigorous version of a systematic review. It is a single piece of evidence that is summarized and should not be considered a complete representation of the entire body of evidence on a clinical issue. |
| Randomized Controlled Trials | RCT's are clinical trials based on random subject assignment to an experimental or control group. They are considered the gold standard for measuring an intervention's impact across many diverse fields. | Well-designed RCTs are superior to other study designs in estimating an intervention’s true effect. |
| Cohort Studies | Cohort studies have a control group where a group of people with something in common (a cohort) are followed. This group is compared to another group with similar characteristics/circumstances, with the exception of the factor being investigated. | Cohort studies are observational and not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study. |
| Case Reports | Case reports are a collection of reports on the treatment of individual patients or a report on a single patient. | They have little statistical validity because they are individual reports of cases and use no control groups to compare outcomes. |
| Expert Opinion | Expert opinion is an authoritative opinion of an expert. | An expert opinion provides anecdotal information from someone with clinical experience which can be valuable; however it is not considered to be evidence-based information. |
It can be difficult to tell the difference between original research articles and review articles. You can use this chart to help you.
You can also read the article abstract for clues. If you see phrases such as "we tested" and "in our study, we measured", it will tell you that the article is reporting on original research.
The following chart offers a brief summarization oft the review types featured in this guide along with their perceived strengths and weaknesses. For more, full-fledge explanation, please visit each review's corresponding page within this guide.
| Type | Description | Strengths | Weaknesses |
| Literature Review | Generic term; published materials that offer an examination of recent/current literature. Can cover wide range of topics at various levels of completeness and comprehensiveness | Brings together what has been accomplished without repetition and identifying gaps or omission all within a summation | No set method to ensure completeness or comprehensiveness. Includes high chance of bias |
| Critical Review | Aims to demonstrate that the writer has extensively researched the literature and critically evaluated it for quality. Goes beyond simple description to include a degree of analysis and synthesis. Typically results in the formation of hypothesis or model | Used to look at the entire body of work on a given topic. Can be used to introduce an idea, resolve competing theories, or call for testing on a topic. | Its methods do nor require the same degree of systematicity when compared to other review methodologies. No requirement to present the methods of the search, synthesis, and analysis explicitly. The focus is on the conceptual contribution of the included literature, not on formal quality assessment. Resulting product is a starting point for further evaluation, not an endpoint |
| Integrative Review | Summarizes past empirical or theoretical literature to provide a more comprehensive understanding of a particular phenomenon or healthcare problem; often implemented by nursing research communities |
Commonly includes non-experimental research, such as case studies, observational studies, and meta-analyses, but may also include practice applications, theory, and guidelines. Can help inform healthcare policy and practice |
Combining different types of studies can lead to a lack of thoroughness and an increase in bias. No set method for conducting analysis and synthesis |
| Mapping Review | Map and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in the literature | Enables contextualization of in-depth systematic review process within broader literature and identification of evidence gaps. Can help determine what is needed to make an informed decision on a topic, or if a subset can be reviewed due to theoretical perspective, population group, or setting of the study |
Time constrained, do not usually included quality assessment, and lack synthesis and analysis of more considered approaches. Studies can be characterized at a broad level which may oversimplify the picture regarding studies and their findings |
| Meta-Analysis | Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results | Utilizes small or inconclusive studies into other studies to aid in forming conclusions that the user would otherwise be unable to do | Cannot be better than its included studies allow. Some have argued that the combination of studies is comparing apples and oranges |
| Overview of Reviews | Specifically refers to the a review compiling evidence from multiple viewpoints into one document. Focuses on broad condition or problem for which there are competing interventions. Highlights reviews that address these interventions and their results | Compiles the evidence of multiple reviews to answer a specific question. Creates a balance between macro-scale reviews and reviews that adopt a micro-focus to examine a specific topic thus becoming hyper-specific | Is dependent upon there already being a narrower sub-section of reviews on the topic |
| Rapid Review | Assessment of what is already known about a policy of practice issue. Uses systematic review methods to search and critically appraise existing research | Designed to be completed quickly by using less systematic search strategies, looking at other reviews but not grey literature | Shortened time frame leads to limited quality assessment which increases the risk of including biased or low quality research |
| Scoping Review | Preliminary assessment of potential size and scope of available research literature. Seeks to identify nature and extent of research evidence | Are used to determine if a full systematic review will be necessary to form a conclusion |
Possesses a higher risk of being biased |
| Systematic Review | Seeks to systematically search for, appraise, and synthesis research evidence, typically adhering to strict guidelines on the conduct of a review | Comprehensive, seeks to include all knowledge, including grey literature, on a given topic | Time-intensive and lengthy process. Strict inclusion/exclusion criteria that can be restrictive and/or hinder wide scale application of methodology when providing conclusions |
| Systematized Review | Review features components of the systematic review process while stopping short of systematic review. Typically conducted for postgraduate work (thesis/dissertation/capstone) | Models the systematic review process and allows the author to demonstrate an awareness of the systematic review process and technical proficiency in the component steps. May form the basis for a more extensive work | The quality assessment and the synthesis are usually less defined, this can lead to bias. Such reviews do possess a greater likelihood of bias than those that adhere more strictly to guidelines on the conduct of systematic reviews |
Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.
For any study that you wish to include in your paper, you must first assess its quality and validity. This critical evaluation will allow you to:
There are three questions that you should apply to any study:
There are a number of checklists that you can use to assist with determining the quality of a study. Below are some recommended resources.
Users' Guides to the Medical Literature: a Manual for Evidence-Based Clinical Practice, 3E by
Publisher's Note: Products purchased from Third Party sellers are not guaranteed by the publisher for quality, authenticity, or access to any online entitlements included with the product. The leading guide to the principles and clinical applications of evidence-based medicine--updated with new examples and new chapters A Doody's Core Title for 2019! Revised and updated to reflect the latest in medical research and evidence-based resources Practical focus and organization to guide clinicians through the fundamentals of using the medical literature to the more advanced strategies and skills for use in patient care, using the key questions to assess any new research: What are the results? How serious is the risk of bias? How do I apply the results to patient care? Updated real-world examples drawn from the medical literature New chapters that reflect the changing complexity of medical research and literature, including genetic association studies, systematic reviews and meta-analyses, network meta-analysis, noninferiority trials, quality improvement, and evidence-based medicine and the theory of knowledge New emphasis on understanding the role of patient preferences and preappraised resources that provide updated evidence and evidence-based recommendations for practice
1. Did the review explicitly address a sensible question?
2. Was the search for relevant studies detailed and exhaustive?
3. Was the risk fo bias of the primary studies addressed?
4. Was the selection and assessment of studies reproducible?
1. Were the patients randomized?
2. Was group allocation concealed?
3. Were patients in the treatment and control groups similar with respect to known prognostic factors?
4. Were 5 important groups (patients, care givers, collectors of outcome data, adjudicators of outcome, and data analysts) aware of group allocation?
5. Outside of experimental intervention, were the groups treated equally?
6. Was follow-up complete?
7. Were patients analyzed in the groups to which they were randomized?
Key issues for therapy studies -- FRISBE
1. Did the clinicians face diagnostic uncertainty?
2. Did investigators compare the test to an appropriate, independent reference standard?
3. Were those interpreting the test and reference standard blind to the other result?
4. Did the investigators perform the same reference standard to all the patients regardless of the results of the test under investigation?
1. Was the sample of patents representative at a well-defined point in the course of the disease or disorder?
2. Were the patients sufficiently similar with respect to prognostic factors?
3. Was the follow up complete?
4. Were outcomes criteria objective and unbiased?
Includes what to consider for a COHORT STUDY and a CASE CONTROL STUDY
1. In a COHORT STUDY did the exposed and control group start and finish with the same risk for outcome?
2. In a CASE CONTROL STUDY did the cases and control group have the same risk (chance) of being exposed in the past?
Calculate the odds ratio (OR) -- a measure of association between an exposure and an outcome. Represents the odds that a person with the outcome was exposed compared to the odds that a person without the outcome was exposed.
Experimental Event Rates (EER): the outcome present/total in an experimental group
Control Event Rate (CER): the outcome present/total in control group
Absolute Risk Reduction (ARR): an absolute comparison of risks. Tells you how much lower the modified risk is than the starting risk. Subtracts the event rates. control/placebo group (starting risk) - experimental group (modified risk)
Absolute Risk Increase (ARI): the arithmetic difference the rates of events in the experimental and control groups. EER - CER
Relative Risk Reduction (RRR): a relative comparison of risks. Tells you how much lower the modified risk is relative to the starting risk. Absolute risk reduction / control group (starting risk)
Relative Risk Increase (RRI): the proportional difference in risk between the rates of events in the control group and the experimental group. RRI is usually a larger number than the ARI . CER - EER / CER
Number Needed to Treat (NNT): the number of patients that need to be treated with the experimental treatment compared to the control treatment for 10 years in order ot have one patient experience a good outcome. 1 / absolute risk reduction (ARR)
Numbers Needed to Harm (NNH): the number of patients that a clinician would have to treat with the experimental treatment over the specific period of time to report one additional patient with an adverse outcome. Numbers Needed to Harm (NNH) = 1 / absolute risk increase (ARI)
Calculate the risk ratio/relative risk (RR) -- the ratio of the probability of an outcome occurring in an exposed group compared ot the probability of the outcome occurring in a non-exposed group
Calculate the odds ratio (OR) -- a measure of association between an exposure and an outcome. Represents the odds that a person with the outcome was exposed compared to the odds that a person without the outcome was exposed.
Adapted from: Guyatt, GH. Users' guides to the medical literature: a manual for evidence-based clinical practice. 3rd edition. McGraw-Hill, 2015.
