Which of the following research designs is also known as ex-post facto design?

DSSSB October 2024

Nursing Research & Statistics

Medium

Appeared in: DSSSB October 2024

Explanation

Ex-post facto research, meaning "after the fact," investigates a phenomenon where the independent variable has already occurred and cannot be manipulated by the researcher.
This type of study is classified as quasi-experimental because it attempts to establish a cause-and-effect relationship but lacks random assignment of subjects to groups.
The design involves comparing pre-existing groups (e.g., those exposed and not exposed to a factor) to infer potential causes for a present condition.
It is a common design in social sciences and nursing when experimental manipulation is unethical or impossible.

Option B: A true experimental design requires both manipulation of the independent variable by the researcher and random assignment of participants to control and experimental groups.
Option C: While ex-post facto research does examine correlations between variables, its primary goal is to explore potential causal links. A purely correlational design simply measures the strength and direction of a relationship without implying causality.
Option D: A descriptive design aims to systematically describe the characteristics of a population or phenomenon. It does not investigate relationships between variables or attempt to infer causality.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of Research Designs as background academic context rather than a clinical decision trigger.
For nurses, understanding different research designs is fundamental to practicing evidence-based care. It allows them to critically appraise research articles and determine the strength of the evidence.
Many questions in nursing and healthcare cannot be studied with true experiments due to ethical constraints (e.g., you cannot ethically assign people to smoke). Therefore, quasi-experimental designs like ex-post facto are crucial for studying the effects of risk factors and harmful exposures.
What if? - If a nurse is reading a study that links a past dietary habit to a current health outcome without random assignment, they should recognize it as an ex-post facto (quasi-experimental) study and understand that while it suggests a link, it does not prove causation as strongly as a randomized controlled trial would.

How to Approach the Question

First, understand the term 'ex-post facto'. It is Latin for 'after the fact'. This is a major clue that the research looks at something that has already happened.
Next, consider the core characteristics of an ex-post facto study: the researcher cannot manipulate the independent variable, and there is no random assignment. The goal is to find a potential cause for an existing effect.
Evaluate the options based on these characteristics. A 'true experiment' requires manipulation and randomization, so it's incorrect.
A 'descriptive' study just describes things, it doesn't look for causes, so it's incorrect.
The choice is between 'quasi-experimental' and 'correlational'. While the study involves correlation, its attempt to infer causality by comparing groups makes it a 'quasi' (or 'almost') experiment. This aligns it more closely with quasi-experimental design.

Concept Tested & Keywords

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E6 NursingResearch Suresh Sharma 5e Part 1 pp. 177-179, 161-163, 180-182