Non-Experimental Designs:
Research
design is a set of decisions that make up the master plan specifying the
methods and procedures for collecting and analyzing the needed information.
Design
chosen depends on: Type of problem,
Knowledge already available about the problem and Resources available for the
study.
Non-Experimental
study designs describe existing
phenomena without manipulating conditions to affect subjects’ responses and
there are no manipulations of an independent variable. Investigates current
status of something (the way things are or were).
All
the research questions cannot be answered by experimental designs because there
are many variables can’t be manipulated either technically or ethically, such
studies are done through Non Experimental research designs. Variables such as
birth weight, body temperature, and ethnicity cannot be manipulated
technically. Experimenting one group by providing specific care and withholding
for another group poses ethical constraints1.
Generally
an experimental study is planned based on a casual relationship established
through a non experimental design. Strong experimental interventions are
planned with the findings if it is suitable for experimentation or if not
suitable it remains as a primarily a descriptive study.
Definition:
Non-Experimental
research design is one of the broad categories of research designs, in which
the researcher observes the phenomena as they occur naturally, and no external
variables are introduced. It is a research design in which variables are not
deliberately manipulated, nor is the setting controlled.
Purposes of Non-experimental research design:
} Exploration and description
of phenomena in real life situations
} Used to develop theory
} Identify problems
} Make decisions /determine
what others in similar situations are doing.
Reasons for undertaking Non-experimental studies:
} Number of human
characteristics/ independent variables are not subject to experimental
manipulation or randomization
} Some variables cannot
ethically be manipulated
} For some research, it is not
practical to conduct a true experiment/manipulate variables
} For some situations, it is
more realistic to explore phenomena in more natural manner.
} Non-experimental research is
often needed to scope out the experimental one.
Steps in Non-experimental Research2:
1.
Determine the research problem and hypotheses to be tested.
2.
Select the variables to be used in the study.
3.
Collect the data.
4.
Analyze the data.
5.
Interpret the results.
Types of Non-experimental
Research:
The classifications of non-
experimental research are3:
a.
Ex post facto,
b.
Correlational,
c.
Descriptive,
d.
Comparative
e.
Survey
f.
Historical
g.
Case study
a.
Ex Post
Facto research:
Ex Post Facto - The meaning
of this Latin term is “from after the fact”. This expression is meant to
indicate that the research in question has been conducted after the variations
in the independent variable have occurred in the natural course of events. Ex
Post Facto research attempts to understand relationships among phenomena as
they naturally occur, without any researcher intervention. The researcher has
no control over the independent variable because it has already occurred4.
Advantages of Ex Post Facto research:
·
Allows for establishment of a differential effect.
·
Similar to co-relational designs.
·
Offers a higher level of control
Disadvantages of Ex Post Facto research:
·
Lack of control on variables
·
Unable to draw casual linkage
·
Problem of alternative hypothesis
b.
Correlational research:
The term Correlational
research refers to finding the interrelationship between two variables that is
a tendency of for variation in one variable to be related to variation in
another. For example in human adults, height and weight tent to be correlated.
All quantitative research
that is not simply descriptive is interested in relationships. Relationships
are reported as positive and negative correlations. Relationships studied by
comparing different groups or correlating two or more variables.
Allow us to identify possible
causes of critical attributes (student achievement, teachers’ instruction, and
administrative leadership). Help us identify variables that may need to be
investigated further. Correlational research allows
the researcher to predict the value of one variable from the value of a second
variable.
Advantages of Correlation research:
·
Increased flexibility when investigating complex relationships among
variables.
·
Efficient and effective method of collecting large amount of data.
·
Potential for practical application in clinical settings.
·
Potential foundation for future experimental studies.
·
Framework for exploring relationships that are not manipulated.
Disadvantages of Correlation research:
·
Unable to manipulate variable of interest.
·
No randomization in sampling.
·
Generalizability decreased as dealing with
pre-existing groups.
·
Unable to determine a casual relationship (doesn’t prove causation)
because of the lack of manipulation, control and randomization.
c.
Descriptive
research:
The purpose of descriptive
study is to observe, describe and document aspects of a situation as it
naturally occurs and sometimes to serve as a starting point for hypotheses
generation or theory development.
Characteristics of Descriptive
research:
·
Describe a phenomenon (Levels of achievement, dropout rates)
·
Use frequencies, percentages, averages or variability to describe
·
Present data through graphs, tables, or other visual images
·
Make no conclusions about relationships
Advantages of Descriptive research:
·
Large amount of sample can be obtained from a large population.
·
Economical manner.
·
Surprisingly accurate.
Disadvantages of Descriptive research:
·
Information tends to be superficial as breath is emphasized.
·
Researcher must be expert in sampling technique, questionnaire, tool
construction, and interviewing and data analysis to produce a reliable and valid
study.
·
Time consuming in nature with more number of samples.
·
Costly
d.
Comparative
research:
Comparative design involves comparing and contrasting
two or more samples of study subjects on one or more variables, often at a
single point of time.
Characteristics of Comparative
Studies:
Ø Compare two or more groups on
a variable
v Relationship between gender
and school grades
v Relationship between learning
style and achievement
Ø Do not establish causal
relationships (no cause/effect)
v Variables may affect or influence,
but cannot say they “cause”
Ø Can serve as basis for
predictions
e.
Survey research:
A
survey is a research design which is used to collect information from different
subjects within a given population having same characteristics of interest. If
a survey is conducted on a sample of population, it is called sample survey,
and if the entire population is involved, it is called a population survey,
such as censuses, etc.
Survey research is a popular method of collecting
data for non-experimental designs. Investigator selects group of respondents,
collects and analyzes information to answer research questions. Subjects
selected from larger population using probability sampling or entire population
may be included. Data reported as incidence, frequency, and distribution of
characteristics.
Surveys
obtain information the sample of people in the means of self – reports,
Personal interviews, Telephonic interviews and Questionnaires
Depending
on the nature of phenomenon under study: Surveys are classified as descriptive,
exploratory, comparative, and correlational surveys.
i.
Descriptive Survey: It is undertaken to describe the frequency of occurrence of a
phenomenon rather than to study relationships
ii.
Exploratory survey: It is the survey of a phenomenon, and its related factors, about which
much is not known.
iii. Comparative
survey: Comparing and contrasting the
existence of a certain phenomenon in two or more groups is done by comparative
surveys.
iv. Correlational survey: It is
a study of the relationship between two or more variables in a natural setting
without manipulation or control.
Based
on the method of data collection, survey researches can be classified as
written, oral, and electronic surveys.
i.
Written survey:
In a written survey, data are collected with the help of written, structured
tools, such as questionnaires, opinionnaires, etc.
ii.
Oral survey:
Data in an oral survey is collected by using face to face or telephonic
conversation or oral interview with respondents.
iii. Electronic
Survey: When data is collected by
using electronic means such as electronic-mail messages (Emails), web forms,
mobile short-message services (SMS), etc., it is known as electronic survey5.
f.
Historical
research:
The historical method is
employed by researchers who are interested in reporting events and/or
conditions that occurred in the past. An attempt is made to establish facts in
order to arrive at conclusions concerning past events or predict future events6.
g.
Case Study
research:
Case study is also known as
case report is an intensive analysis of an individual unit (e.g. a person,
group or event) stressing developmental factors in relation to context. The
case study is common in social sciences and life sciences.
Case study may be descriptive
or explanatory. The explanatory type is used to explore the causation in order
to find the underlying principles. They may be prospective and retrospective.
Strength and Scope of Non-experimental design:
The non-experimental design generally considered to
be the weakest design. But, gives us plenty of opportunity to understand,
describe, and explore the phenomena. Hence, it is very popular in social and
life science research (Fig 1). The
diagram mentioned below explains both the strength and scope of
non-experimental design.
Weakest Design Scope & Practicality Strength Strongest Design
