Case Study | Definition, Examples & Steps
A case study is a detailed, in-depth exploration of a subject. This subject, or “case,” could be just about anything: an individual, a group, a historical event, and so on.
Case study definition
A case study is an in-depth investigation into a phenomenon, which could be a person, group, place, or event. The purpose of case studies is to gain an in-depth understanding of a topic in a real-world setting. This holistic understanding might guide decisions in similar future situations or be used to propose solutions to a problem (action research is another option when using research to solve a real-world problem).
Case studies often combine data from multiple sources to gain holistic insight into a topic. Though case studies generally involve qualitative methods, quantitative methods may also be used. For example, a case study on the impact of bike lanes in a city may combine traffic data (quantitative) with interviews with cyclists and other residents (qualitative).
Case study types and examples
Though case studies can be classified in many different ways, three of the most common types are intrinsic, instrumental, and collective.
Intrinsic case study
An intrinsic case study focuses on a unique or exceptional case, which is chosen for its inherent significance. The purpose of an intrinsic case study is to better understand this particular case rather than to gain a more general understanding of a broader topic or phenomenon. However, insight from intrinsic case studies can still help inform more general theories.
In this example, the natural disaster response itself is of interest to the town; it has intrinsic significance.
Instrumental case study
An instrumental case study focuses on a particular person, place, group, or event. However, unlike an intrinsic study, which seeks to understand the case itself, the overarching purpose of an instrumental case study is to gain a better understanding of a broader topic.
Scientists studied H.M.’s cognitive abilities extensively. They gained a detailed understanding of the limitations someone without a hippocampus faced when remembering and learning new information. These instrumental case studies improved our understanding of how different parts of the brain contribute to learning and memory.
Collective case study
A collective case study involves studying several cases (generally three or more), either simultaneously or sequentially. These cases might all be from the same location (e.g., multiple patients from one hospital) or from multiple sites; a collective case study is therefore often called a multi-site case study.
The aim of a collective case study is similar to that of an instrumental case study: the researcher wants to gain a broader understanding of a topic. However, studying multiple cases can provide a broader perspective on a topic than a case study that is limited to just one case.
Note that these types of studies are not mutually exclusive—elements of different types may be present in a single study. For example, the case study of H.M. could be considered both intrinsic (his case was interesting in its own right) and instrumental (it helped researchers gain a better understanding of how the brain works).
How to conduct a case study
Though the specific steps you follow will depend on the type of case study you are conducting, the following steps generally apply to most case studies.
1. Define the research question and case
A clearly defined research question is instrumental to an effective case study. Once you’ve created a research question that is grounded in existing literature, you can determine the required scope of your case study. You should consider factors such as the relevant time period, duration, location, and demographics of your ideal case.
2. Select the case(s) to study
At this point, you should have a clear understanding of which characteristics your case needs to have. This information, along with your research question, will guide your selection of one or more cases to study.
For an intrinsic case study, the case is selected for its uniqueness or interest. For an instrumental or collective case study, you should choose a case (or cases) that will allow you to study your chosen topic effectively. This may be a “typical” case that best represents your topic of interest; however, an atypical case may also be helpful if you hope to test hypotheses or generate new theories.
3. Collect data
Data collection can be quite intensive for a case study. You want to ensure that you’re gathering information that will provide you with holistic insight into your chosen topic. Combining multiple types of data (qualitative and quantitative) from different sources can improve the test validity of your work; this practice is called triangulation.
4. Describe and analyze the case(s)
Because case studies involve rich datasets from multiple sources, data analysis can be lengthy and complicated. When analyzing data from multiple sites, you can consider analyzing each site separately before combining results.
In general, it’s a good practice to organize all data and familiarize yourself with it before beginning analysis. Be sure to document your analysis process and be prepared to explain these steps and the reasoning behind any conclusions to whomever will be reading or reviewing your work.
5. Write up your results
Once you’ve completed these steps, you can move on to writing up your case study and sharing your findings. How you write up your case study will depend on your field and research question. Some are structured like a standard research paper, while others follow a more narrative approach.
Regardless of the structure of your report, it’s important to provide an overview of any relevant literature, include contextual information about your case(s), and clearly outline your chosen analysis and conclusions.
Pros and cons of case studies
Any research method has its advantages and disadvantages. Keep the following pros and cons in mind when considering whether to conduct a case study:
- Rich insight: The rich datasets of case studies can help a researcher gain a detailed and nuanced understanding of a topic.
- High test validity: Because case studies collect several types of data and study something in their natural setting, it’s likely that they are capturing the concept they’re targeting.
- Time consuming: Especially when combining data from multiple sites, it can take a long time to collect and analyze the data necessary for a case study.
- Limited generalizability: Although focusing on just one case can afford a detailed understanding of a topic, the findings from a case study may not generalize to more general populations or circumstances.
Frequently asked questions about case studies
- What are the types of case studies?
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Though case studies can be classified in many ways, the most common types are intrinsic, instrumental, and collective case studies.
Intrinsic case studies focus on a specific subject (i.e., case). The point of such studies is to learn more about this specific subject rather than to generalize findings.
Instrumental case studies also focus on a single subject, but the intent is to generalize findings to a broader population.
Collective case studies have the same purpose as instrumental case studies—to use findings to increase one’s understanding of a broader topic—but they include multiple cases.
- What is triangulation in qualitative research?
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Triangulation involves using a combination of data or techniques to answer a research question. Triangulation can help you confirm the validity of your findings. This can be helpful in qualitative research, which is often subjective and vulnerable to bias.
Types of triangulation include the following:
- Data triangulation: uses data from different sources
- Investigator triangulation: has multiple people analyze data
- Theory triangulation: uses different theoretical frameworks to analyze data
- Methodological triangulation: uses different approaches to study the same phenomenon
- What is a case study example in psychology?
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Case studies have historically been used in psychology to understand rare conditions. For example, Phineas Gage was a railroad worker who had an iron rod driven through his head in an accident and miraculously survived. However, this accident drastically altered his personality and behavior for the remaining 12 years of his life.
Detailed studies of Phineas Gage helped scientists realize that different areas of the brain have specific functions. This famous case study is an example of how studying one individual in detail can provide insights that drive the formation of broader theories.
