Choosing a Study Design

Written and curated by Emily Potts, MS, Jiying Han, MS, and Pam Factor-Litvak, PhD. 

Overview

In quantitative research, study designs can be broadly classified into two main categories: experimental and observational. Experimental designs involve the assignment of treatment, ideally in a randomized controlled trial (RCT) setting, while observational designs allow researchers to quantify associations and trends without intervening directly. Examples of observational designs include cross-sectional studies, cohort studies, and case-control studies. Beyond these, researchers may also encounter quasi-experimental, qualitative, mixed-method, and meta-analysis designs, each serving unique research needs. While this list is not exhaustive, it presents an intuitive starting point for planning a study and suggests seeking study design and statistical consultation early in the process if necessary. Understanding the basics of study design empowers researchers to choose an appropriate method to feasibly address their primary question, but also considers practical constraints such as time, resources, and ethical considerations, thereby promoting the robustness, validity, and reliability of their findings.