FAQS: Types of Research
1. Case Study / Case Series
A case study (or case report) reports on a single example which is generally an “interesting” or “unusual” patient or situation.
A case series is a study reporting on a consecutive collection of patients treated in a similar manner.
2. Controlled Clinical Trial
Involves one or more test treatments, at least one control treatment, specified outcome measures for evaluating the studied intervention, and a bias-free method for assigning patients to the test treatment. Control measures include placebos, active medicines, no-treatment, dosage forms and regimens, historical comparisons, etc. Methods for assigning patients to the best treatment include: coin flips, odd-even numbers, patient social security numbers, days of the week, medical record numbers, or other such pseudo- or quasi-random processes.
3. Cross Sectional Study
An epidemiological study that examines the relationship between diseases (or other health related characteristics) and other variables of interest as they exist in a defined population at one particular time.
The temporal sequence of cause and effect cannot necessarily be determined in a cross-sectional study. This contrasts with longitudinal studies which are followed over a period of time
4. Literature Review
A type of secondary research that examines the body of literature on a topic, including published material, grey literature, and clinical research or case studies.
5. Meta-Analysis
A statistical technique that summarizes the results of several studies into a single estimate of their combined result. It is a key element of many systematic reviews. It is also what is meant by the phrase, “pooling data.”
6. Peer Review
An editorial process used by certain journals to evaluate research articles or studies submitted for publication. A panel of experts (peers) anonymously assesses the methodological quality, pertinence, value, etc. of submissions, often offering suggestions for revision before making a final decision to reject or accept them. Journals using this process are called peer reviewed (or refereed).
7. Primary Resources
An investigation that collects original (primary) data. In scientific and medical research, the study data are then published in a scholarly journal as a primary research study. The authors of the article reporting the study results are also the principal investigators who conducted the research. One example of a primary research study is a randomized controlled trial.
8. Qualitative Research
“[D]erives data from observation, interviews, or verbal interactions and focuses on the meanings and interpretations of the participants.” Qualitative studies, such as case studies or case reports, are conducted with no control group involved.
9. Quantitative Research
Studies things that can be counted, and often uses statistical manipulations to process data and summarize results. The main types of quantitative research are: descriptive; correlational/predictive; quasi-experimental/experimental; single-subject; and meta-analysis.
10. Randomized Controlled Trial
The same as a controlled clinical trial, except more rigorous mathematical techniques, such as the use of a random-numbers table or computer- generated numbers, are used for randomization of study participants.
11. Secondary Resources
Presents a discussion, summary, analysis or review of primary research. Examples of secondary research from the medical field are systematic reviews and meta-analyses.
12. Systematic Review
Begins with a clearly formulated question and uses systematic methods to identify, select and critically appraise relevant research studies; data from the studies that are included in the review are then collected and analyzed. Statistical methods, such as meta-analysis, may or may not be used in the analysis of results.