Once you have your focused question, it's time to decide on the type of evidence you need to answer it. Understanding the types of research will help guide you to proper evidence that will support your question.
The data that is obtained during a study that has been conducted. Examples include surveys, information from focus groups, questionnaires, and the like. Primary research presented in the results of randomized controlled trials and observational studies.
The summary and analysis of already existing research. Examples include systematic reviews, meta-analyses, review articles, and textbooks.
Collecting and analyzing non-numerical data to understand concepts, opinions, or experiences.
Collecting and analyzing numerical data to describe characteristics and find correlations.
As you move up the pyramid, the study designs are more rigorous and are less biased.
Intervention/Therapy: Questions addressing the treatment of an illness or disability.
Etiology: Questions addressing the causes or origins of disease (i.e., factors that produce or predispose toward a certain disease or disorder).
Diagnosis: Questions addressing the act or process of identifying or determining the nature and cause of a disease or injury through evaluation.
Prognosis/Prediction: Questions addressing the prediction of the course of a disease.
Intervention/Prevention: RCT > Cohort Study > Case Control > Case Series
Therapy: RCT > Cohort > Case Control > Case Series
Prognosis/Prediction: Cohort Study > Case Control > Case Series
Diagnosis/Diagnostic: Prospective, blind comparison to Gold Standard
Etiology: RCT > Cohort Study > Case Control > Case Series
|Case Reports or Case Studies||Detailed reports or collections of reports for individual patients.|
|Case Control Studies||Studies in which patients who currently have a condition are compared to those who do not. Researchers look back retrospectively to identify possible exposures. Case control studies are less reliable than randomized control trials because of the lack of ability to demonstrate causal relationships.|
|Cohort Studies||Identifies and follows two groups of patients, one group who has received an exposure of interest and one who has not.|
|Randomized Control Trial (RCT)||A scientific study that randomly assigns participants to a test or control group. Primary data is generated and outcomes are compared between the two groups.|
|Systematic Review||A review of all the available literature on a specific topic that has been systematically searched for, critically appraised, and summarized; usually focused on a answering a specific clinical question|
|Meta-Analysis||Taking a systematic review a step further and applying a quantitative statistical analysis to the methodology used in the included literature to test for statistical significance.|
|Clinical Practice Guidelines||Provide steps and tools for appropriate diagnosis and treatment; based on an examination of current evidence within the paradigm of evidence-based medicine.|
Q1. What was the aim of the study?
Q2. If analytic, was the intervention randomly allocated?
For observational study the main types will then depend on the timing of the measurement of outcome, so our third question is:
Q3. When were the outcomes determined?
from Centre for Evidence-Based Medicine https://www.cebm.net/2014/04/study-designs/