Social Science Research

1. Lecture 05
Research Design: Quantitative Approach to Research
Professor Dr. Sadik Hasan
University of Dhaka

2. Introduction
• The term “research design” refers to the way an investigator applies a logical
structure to his/her research project. The function of this step in the research
process is to make sure that the data gathered are sufficient and appropriate for
answering the research questions completely and unambiguously.
• It is important to keep in mind that research design is not the same thing as
research methods. Methods, on the other hand, are the ways that data are
collected.
• Hakim (2000) identified eight types of study designs.
• Bryman (2001) also pinpointed five types of research designs in social sciences.
• Thus, to help clarify this great variety of options in research designs, all of these
are grouped into two broad approach categories: qualitative (positivist) and
quantitative (post-positivist) designs. Each approach supports a variety of designs
and methods for gathering data; and each allows the researcher a variety of
analysis and interpretation actions.

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• In deciding what strategy to follow in a quantitative design, political science researchers
usually seek answers to these six basic questions (Miller, 1991):
• What characteristics of the people in my sample (e.g., demographic differences)
distinguish them from other groups or subgroups of people who I might have
included in my study?
• Are there any differences in the subgroups contained in this sample that might
influence the way the questions are answered or opinions that are offered?
• Is there a statistically significant difference in the answers of any groups or
subgroups in this sample, or did they all answer the questions in roughly the same
way?
• What confidence can I have that any difference that I do find did not occur by
chance?
• Is there any association between two or more variables in my study? Is it relevant?
Is it significant?
• If there is any relationship between two or more variables, is it possible to measure
how strong it is and whether it is a positive or negative relationship?

4. Schematic Representation of Quantitative Research Design Process
Establish Research
Objectives
Select a Quantitative
Research Design
Design Data-gathering
Instrument
Gather, Analyze, and
Interpret Data
Report Study Findings
Descriptive Research Causal Research
Exploratory Research

5. Types of Quantitative Research Design
• Depending on their research objective, researchers select from three types of
quantitative research designs:
• Exploratory Designs: These are small-sample designs used primarily for
gaining insights and ideas about research problems and the variables and
issues associated with those problems. Such studies are sometimes called as
“Pilot Studies”.
• It helps the researcher gain greater understanding of the problem for which
more information is needed.
• Data gathering in exploratory research may involve quantitative, qualitative,
or a combination of strategies. Data may come from both primary and
secondary sources.

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• Descriptive Designs: These are used to develop a “snapshot” of a
particular phenomenon of interest. It typically involves large samples.
• It provides a description of an event, or help define a set of attitudes,
opinions, or behaviors that are observed or measured at a given time and
in a given environment.
• The focus of this is on the careful mapping out of a circumstance,
situation, or set of events to describe what is happening or what has
happened.
• It may be either cross-sectional or longitudinal.

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▪ Cross-sectional design is a one-shot assessment of a sample of
respondents. Time is an important consideration as the “picture of the
sample” usually varies—sometimes extensively—if the research is
repeated at a later date or conducted with another sample taken from the
same population.
▪ The purpose of cross-sectional design is to determine to what extent
different classes in the sample differ on some outcome (independent)
variable like gender, age groups, income groups, social class groups, ethnic
groups, etc.
▪ Descriptive research that is repeated with the same sample over two or
more-time intervals is known as longitudinal research. The purpose is to
identify and measure change in subjects’ responses.

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• The basic elements of a cross-sectional design are:
• The design measures variations in the responses to independent variables
in the sample. An example is a survey to determine whether women and
men have different attitudes toward a political candidate. Everyone is asked
the same questions; their answers can be tabulated and compared.
• At least one independent variable with at least two categories is used in
the instrument. In the preceding example, the independent variable was
attitudes; categories could be a simple approve/disapprove dichotomy,
or more likely will be measured on something like a five-point scale.
• Data are collected at one point in time. The cross-sectional design is a
“snapshot” measurement with results specific to that moment.
• There is no random allocation of subjects to groups although the total sample
itself will most likely have been randomly selected from a known population.

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• Causal Designs: These designs typically involve planning and conducting
experiments. Causal studies may be either relational or experimental.
• The purpose of relational studies is to identify how one or more variables
are related to one another. They are sometimes called correlational
studies.
• The purpose of an experimental design is to identify the cause or causes of
change in a variable or event—that is, determining “what leads to what”.