TL;DR — Quick Answer
Research can be classified in several ways. By purpose: basic (advancing knowledge) versus applied (solving practical problems). By approach: quantitative (numbers), qualitative (words and meanings), and mixed methods. By objective: descriptive, exploratory, explanatory, and correlational. By data source: primary (collected first-hand) and secondary (existing data). Understanding these types helps researchers choose the right kind of research for their question. Most real studies combine several classifications — for example, applied quantitative descriptive research using primary data.
Research is not a single, uniform activity. It takes many forms, each suited to different questions, goals, and contexts. A scientist testing a new drug, a sociologist exploring lived experiences, a business analyst solving a company problem, and a historian examining archives are all conducting research — but research of very different kinds. Understanding the types of research, and how they are classified, helps researchers identify what kind of research their question requires and choose the appropriate methods.
For students and researchers, knowing the types of research is foundational knowledge. It provides the vocabulary and conceptual map for understanding the research landscape, situating any particular study, and making informed decisions about how to approach a research question. This guide explains the main ways research is classified and what each type involves.
How Research Is Classified
Research can be classified in several different ways, depending on the dimension you focus on. The same study can be described by multiple classifications at once — by its purpose, its approach, its objective, and its data source. These classifications are not mutually exclusive but complementary lenses for understanding a piece of research.
The main classification dimensions are: by purpose (basic versus applied), by approach (quantitative, qualitative, mixed), by objective (descriptive, exploratory, explanatory, correlational), and by data source (primary versus secondary). Let us examine each.
Classification by Purpose
Basic Research
Basic research, also called pure or fundamental research, aims to advance knowledge and understanding for its own sake, without an immediate practical application in mind. It seeks to understand fundamental principles, develop theories, and expand the body of knowledge. Much scientific research exploring how the natural world works is basic research. Its value lies in deepening understanding, which often leads to practical applications later, even when none was initially intended.
Applied Research
Applied research aims to solve specific, practical problems. It applies knowledge to address real-world issues, answer practical questions, or develop solutions. Research to improve a manufacturing process, develop a new product, or address a social problem is applied research. Its value lies in its direct practical utility.
Basic and applied research are complementary: basic research generates the fundamental knowledge that applied research draws upon, while applied research often raises questions that drive further basic research.
Classification by Approach
Quantitative Research
Quantitative research collects and analyses numerical data to measure variables, test hypotheses, and identify statistical relationships. It answers questions about how many, how much, and whether measurable relationships exist, using methods like surveys and experiments analysed statistically.
Qualitative Research
Qualitative research collects and analyses non-numerical data — words, observations, and narratives — to understand experiences, meanings, and phenomena in depth. It answers questions about why and how, using methods like interviews, focus groups, and case studies.
Mixed-Methods Research
Mixed-methods research combines quantitative and qualitative approaches within a single study, drawing on the strengths of both to address questions that benefit from both measurement and deep understanding.
Classification by Objective
Descriptive Research
Descriptive research aims to describe a phenomenon, situation, or population accurately — documenting characteristics, frequencies, and patterns. It answers what is, without explaining causes.
Exploratory Research
Exploratory research investigates a problem that is not yet well understood, seeking initial insights and generating hypotheses. It is appropriate in the early stages of studying a new or unclear topic.
Explanatory Research
Explanatory research, also called causal research, seeks to explain why something happens — identifying causes and effects and the relationships between variables. It answers why and goes beyond describing to explaining.
Correlational Research
Correlational research examines the relationship between variables, determining whether and how strongly they are related, without necessarily establishing causation.
| Classification | Types | Distinguishes By |
|---|---|---|
| By purpose | Basic, Applied | Why the research is done |
| By approach | Quantitative, Qualitative, Mixed | Type of data and analysis |
| By objective | Descriptive, Exploratory, Explanatory, Correlational | What the research aims to do |
| By data source | Primary, Secondary | Where the data comes from |
Classification by Data Source
Primary Research
Primary research involves collecting new, first-hand data directly — through surveys, experiments, interviews, or observations conducted by the researcher. The data is original and gathered specifically for the research at hand. Primary research provides data tailored precisely to the research question but requires more time and resources to collect.
Secondary Research
Secondary research uses existing data that was collected by others — published studies, datasets, records, and reports. The researcher analyses or synthesises data that already exists rather than collecting new data. Secondary research is more efficient and can draw on large existing datasets, but the data was not collected specifically for the research question, which can limit its fit.
How These Classifications Combine
A crucial point is that these classifications are not mutually exclusive. Any real study can be described by all four dimensions simultaneously. For example, a study might be applied (purpose), quantitative (approach), descriptive (objective), and based on primary data (source) — an applied quantitative descriptive study using primary data.
This means that when planning research, you are not choosing one type from a single list, but making decisions along several dimensions: what is the purpose, which approach fits, what is the objective, and where will the data come from. Each decision shapes the research, and together they define the specific kind of study you will conduct.
As Dr. Madhuri Kanojiya, Founder of Empire Research Press, explains: “Understanding the types of research is like learning the vocabulary of a discipline. These classifications are not rigid boxes but complementary lenses — every study has a purpose, an approach, an objective, and a data source. When you can place your research along each of these dimensions, you understand precisely what kind of study you are conducting and why. That clarity guides every subsequent decision about methods, analysis, and interpretation.”
Choosing the Right Type of Research
The right type of research is determined by your research question and goals. Consider: Are you advancing knowledge or solving a practical problem (basic versus applied)? Does your question require measurement or deep understanding (quantitative versus qualitative)? Are you describing, exploring, explaining, or examining relationships (your objective)? Will you collect new data or use existing data (primary versus secondary)?
Answering these questions along each dimension defines the type of research you need. As with research design, the guiding principle is fit — the type of research must suit the question. Let your research question lead these decisions, and the appropriate type of research will become clear.
Conclusion
Research takes many forms, classified by purpose (basic versus applied), approach (quantitative, qualitative, mixed), objective (descriptive, exploratory, explanatory, correlational), and data source (primary versus secondary). These classifications are complementary lenses rather than mutually exclusive categories — every study can be described along all four dimensions at once.
Understanding the types of research provides the conceptual map for navigating the research landscape, situating any study, and choosing the right approach for a research question. When you can identify your research along each dimension, you gain clarity about exactly what kind of study you are conducting — and that clarity guides every decision that follows. Whatever your question, understanding these types is foundational to approaching it well.
Frequently Asked Questions
Q: What are the main types of research?
Research can be classified in several complementary ways. By purpose: basic research (advancing knowledge for its own sake) and applied research (solving practical problems). By approach: quantitative (numerical data), qualitative (words and meanings), and mixed methods (both). By objective: descriptive (describing phenomena), exploratory (gaining initial insights), explanatory (identifying causes), and correlational (examining relationships). By data source: primary (new first-hand data) and secondary (existing data). These classifications are not mutually exclusive — any study can be described along all four dimensions at once.
Q: What is the difference between basic and applied research?
Basic research (also called pure or fundamental research) aims to advance knowledge and understanding for its own sake, without an immediate practical application in mind — it seeks to understand fundamental principles and develop theories. Applied research aims to solve specific, practical problems by applying knowledge to real-world issues. For example, research exploring how a biological process works is basic research, while research developing a treatment based on that knowledge is applied. The two are complementary: basic research generates fundamental knowledge that applied research draws upon, while applied research often raises new questions for basic research.
Q: What is the difference between primary and secondary research?
Primary research involves collecting new, first-hand data directly through surveys, experiments, interviews, or observations conducted by the researcher — the data is original and gathered specifically for the research at hand. Secondary research uses existing data collected by others, such as published studies, datasets, and reports, which the researcher analyses or synthesises. Primary research provides data tailored precisely to the research question but requires more time and resources, while secondary research is more efficient and can draw on large existing datasets, though the data was not collected specifically for the research question.
Q: What is the difference between quantitative and qualitative research?
Quantitative research collects and analyses numerical data to measure variables, test hypotheses, and identify statistical relationships, answering questions about how many, how much, and whether measurable relationships exist — using methods like surveys and experiments. Qualitative research collects and analyses non-numerical data such as words and observations to understand experiences and meanings in depth, answering questions about why and how — using methods like interviews and case studies. The choice depends on whether your research question requires measurement and statistical generalisation or deep understanding of experiences and meanings. Mixed-methods research combines both approaches.
Q: How do I choose the right type of research?
The right type of research is determined by your research question and goals, decided along several dimensions. Ask: Are you advancing knowledge or solving a practical problem (basic versus applied)? Does your question require measurement or deep understanding (quantitative versus qualitative)? Are you describing, exploring, explaining, or examining relationships (your objective)? Will you collect new data or use existing data (primary versus secondary)? Answering these questions along each dimension defines the type of research you need. The guiding principle is fit — the type of research must suit the question, so let your research question lead these decisions.
Article reviewed, edited, fact-checked and approved before publication. — Empire Research Press Editorial Standard