Research types

There are several types of scientific papers, each serving a distinct purpose and evaluation criteria (Peh & Ng, 2008). The classification of research types presented here is based on Röhrig et al. (2009).

Primary research

Primary research refers to original studies in which new data are collected and analyzed:

basic research

Researchers change one factor (e.g., treatment dosage) and observe how it affects another (e.g., tissue response). Since these studies are done on animals or cells in the lab, the results do not always translate directly to humans, but give researchers important clues and a starting point for developing human therapies.
clinical research

In case of experimental research, the goal is to compare treatments within a similar group of patients. Usually, a control group receives a different treatment or a placebo (a harmless treatment that looks real but has no active effect). The ideal design is a randomized, controlled, double-blind clinical trial where patients are assigned by chance and neither the patient nor the researcher knows which treatment is given.

In contrast, obsevational studies rely on individually specified therapy given to a patient. Evaluation is often retrospective. For a rare disease, single-case study (one patient) or case series (group of patients) are possibilities.
epidemiological research

Focused on investigating distribution and historical changes in the frequency of diseases.

Secondary research

Secondary research summarizes findings from existing studies (e.g., in review articles) and does not generate new primary data or primarily present the authors’ personal opinions.

Here are a few examples of ENS studies illustrating different types of research:

Research type	Study type	ENS example
Primary-Basic	Animal Study	In the study by Kang et al., (2025), ENS was induced in a rabbit model via electrocautery, and different amounts of nasal stem cells with a collagen gel were given.
Primary-Clinical	Observational	Berg et al. (2018) reported that temporary intranasal submucosal filler injections altered nasal airflow and improved symptoms in patients with ENS
Secondary	Review	Kim et al. (2024) published a systematic review of treatment options for ENS

Unfortunately, there is an absence of randomized controlled trials for ENS (Hussain et al., 2025). The rarity of ENS, its varied symptoms, and the lack of a standard diagnostic test make conducting randomized controlled trials challenging.

Sources

Peh, W.C., & Ng, K.H. (2008). Basic structure and types of scientific papers. Singapore Medical Journal, 49(7), 522–525. Retrieved from https://pubmed.ncbi.nlm.nih.gov/18695858/

Röhrig, B., du Prel, J.-B., Wachtlin, D., & Blettner, M. (2009). Types of study in medical research. Deutsches Ärzteblatt International, 106(15), 262–268. Retrieved from https://pubmed.ncbi.nlm.nih.gov/19547627/

Kang, Y. J., Park, D. B., Jang, D. W., Lim, M. H., Lee, J. Y., Yoo, S. Y., Kim, S. W., & Kim, D. H. (2025). Optimizing human nasal turbinate stem cell dosage for the effective treatment of Empty Nose Syndrome. Journal of Rhinology, 32(3), 175–183. https://doi.org/10.18787/jr.2025.00021

Hussain, S., Hayat, J., Almhanedi, H., Alherz, M., Ebrahim, M., Lari, A., & Thamboo, A. (2025). A systematic review and meta‑analysis of management options for empty nose syndrome: A proposed management algorithm. Otolaryngology–Head and Neck Surgery, 172(1), 1–12. https://doi.org/10.1002/ohn.929

Berg, M. A., Garcia, G. R., & Senior, B. A. (2019). Use of intranasal submucosal fillers as a transient implant to alter upper airway aerodynamics: Implications for the assessment of empty nose syndrome. Laryngoscope Investigative Otolaryngology, 4(3), 288–296. https://doi.org/10.1002/lio2.261