A research design is the investigator-chosen, overarching study framework that facilitates getting the most accurate answer to a hypothesis or question. Think of research design as similar to the framing of a house during construction. Just as house-framing provides structure and limits to walls, floors, and ceilings, so does a research design provide structure and limits to a host of protocol details.

Tip. The two major categories of research design are: 1) Non-experimental, observation only and 2) Experimental testing of an intervention.

DESCRIPTIVE STUDIES

Non-experimental studies that examine one variable at a time.

When little is known and no theory exists on a topic, descriptive research begins to build theory by identifying and defining key, related concepts (variables). Although a descriptive study may explore several variables, only one of those is measured at a time; there is no examination of relationships between variables. Descriptive studies create a picture of what exists by analyzing quantitative or qualitative

data to answer questions like, “What is [variable x]?” or “How often does it occur?” Examples of such one-variable questions are “What are the experiences of first-time fathers?” or “How many falls occur in the emergency room?” (Variables are in italics.)  The former question produces qualitative data, and the latter, quantitative.

Descriptive results raise important questions for further study, and findings are rarely generalizable. You can see this especially in a descriptive case study: an in-depth exploration of a single event or phenomena that is limited to a particular time and place. Given case study limitations, opinions differ on whether they even qualify as research.

Descriptive research that arises from constructivist or advocacy assumptions merits particular attention. In these designs, researchers collect in-depth qualitative information about only one variable and then critically reflect on that data in order to uncover emerging themes or theories. Often broad data are collected in a natural setting in which researchers exercise little control over other variables. Sample size is not pre-determined, data collection and analysis are concurrent, and the researcher collects and analyzes data until no new ideas emerge (data saturation). The most basic qualitative descriptive method is perhaps content analysis, sometimes called narrative descriptive analysis, in which researchers uncover themes within informant descriptions. Figure 4 identifies major qualitative traditions beyond content analysis and case studies.

Alert! All qualitative studies are descriptive, but not all descriptive studies are qualitative.

Box 1. Descriptive Qualitative Designs

Design	Focus	Discipline of Origin
Ethnography	Uncovers phenomena within a given culture, such as meanings, communications, and mores.	Anthropology
Grounded Theory	Identifies a  basic social problem and the process that participants use to confront it.	Sociology
Phenomenology	Documents the “lived experience” of informants going through a particular event or situation.	Psychology
Community participatory action	Seeks positive social change and empowerment of an oppressed community by engaging them in every step of the research process.	Marxist political theory
Feminist	Seeks positive social change and empowerment of women as an oppressed group.	Marxist political theory