Some of the important concepts relating to Research Design are discussed below:
Relating To Research Design:
Some of the important concepts
relating to Research Design are discussed below:
1. Dependent And Independent Variables:
A magnitude that varies is known
as a variable. The concept may assume different quantitative values like
height, weight, income etc. Qualitative variables are not quantifiable in the
strictest sense of the term. However, the qualitative phenomena may also be
quantified in terms of the presence or absence of the attribute(s) considered.
The phenomena that assume different values quantitatively even in decimal
points are known as ‘continuous variables’. But all variables need not be
continuous. Values that can be expressed only in integer values are called ‘non-continuous
variables’. In statistical terms, they are also known as ‘discrete variables’.
For example, age is a continuous variable, whereas the number of children is a
non-continuous variable. When changes in one variable depend upon the changes
in other variable or variables, it is known as a dependent or endogenous
variable, and the variables that cause the changes in the dependent variable are
known as the independent or explanatory or exogenous variables. For example, if
demand depends upon price, then demand is a dependent variable, while price is
the independent variable. And, if more variables determine demand, like income
and price of the substitute commodity, then demand also depends upon them in
addition to the price of original commodity. In other words, demand is a
dependent variable which is determined by the independent variables like price
of the original commodity, income and price of substitutes.
2. Extraneous Variables: The independent variables which
are not directly related to the purpose of the study but affect the dependent
variables, are known as extraneous variables. For instance, assume that a
researcher wants to test the hypothesis that there is a relationship between
children’s school performance and their self-confidence, in which case the
latter is an independent variable and the former, a dependent variable. In this
context, intelligence may also influence the school performance. However, since it
is not directly related to the purpose of the study undertaken by the researcher, it would be known as an extraneous
variable. The influence caused by the extraneous variable(s) on the dependent
variable is technically called the ‘experimental error’. Therefore, a research
study should always be framed in such a manner that the influence of extraneous
variables on the dependent variable/s is completely controlled, and the
influence of independent variable/s is clearly evident.
3. Control: One of the most important
features of a good research design is to minimize the effect of extraneous
variable(s). Technically, the term ‘control’ is used when a researcher designs
the study in such a manner that it minimizes the effects of extraneous
variables. The term ‘control’ is used in experimental research to reflect the
restrain in experimental conditions.
4. Confounded Relationship: The relationship between the
dependent and independent variables is said to be confounded by an extraneous
variable, when the dependent variable is not free from its effects.
5. Research Hypothesis: When a prediction or a
hypothesized relationship is tested by adopting scientific methods, it is known
as research hypothesis. The research hypothesis is a predictive statement which
relates to a dependent variable and an independent variable. Generally, a
research hypothesis must consist of at least one dependent variable and one
independent variable. Whereas, the relationships that are assumed but not to be
tested are predictive statements that are not to be objectively verified, thus
are not classified as research hypotheses.
6. Experimental and Non-experimental Hypothesis Testing Research: When the objective of a research
is to test a research hypothesis, it is known as hypothesis-testing research.
Such research may be in the nature of experimental design or non-experimental
design. The research in which the independent variable is manipulated is known
as ‘experimental hypothesis-testing
research’, whereas the research in which the independent variable is not manipulated is termed as ‘non-experimental
hypothesis-testing research’. For example, assume that a researcher wants to
examine whether family income influences the school attendance of a group of
students, by calculating the coefficient of correlation between the two
variables. Such an example is known as a non-experimental hypothesis-testing
research, because the independent variable - family income is not manipulated
here. Again assume that the researcher randomly selects 150 students from a
group of students who pay their school fees regularly and then classifies them
into two sub-groups by randomly including 75 in Group A, whose parents have
regular earning, and 75 in Group B, whose parents do not have regular earning.
Assume that at the end of the study, the researcher conducts a test on each
group in order to examine the effects of regular earnings of the parents on the
school attendance of the student. Such a study is an example of experimental
hypothesis-testing research, because in this particular study the independent
variable regular earnings of the parents have been manipulated.
7. Experimental And Control Groups: When a group is exposed to usual
conditions in an experimental hypothesis-testing research, it is known as ‘control
group’. On the other hand, when the group is exposed to certain new or special
condition, it is known as an ‘experimental group’. In the afore-mentioned
example, Group A can be called as control group and Group B as experimental
group. If both the groups, A and B are exposed to some special feature, then
both the groups may be called as ‘experimental groups’. A research design may
include only the experimental group or both the experimental and control groups
8. Treatments: Treatments refer to the different
conditions to which the experimental and control groups are subject to. In the
example considered, the two treatments are the parents with regular earnings
and those with no regular earnings. Likewise, if a research study attempts to
examine through an experiment the comparative effect of three different types
of fertilizers on the yield of rice crop, then the three types of fertilizers
would be treated as the three treatments.
9. Experiment: Experiment refers to the process
of verifying the truth of a statistical hypothesis relating to a given research
problem. For instance, an experiment may be conducted to examine the yield of a
certain new variety of rice crop developed. Further, Experiments may be
categorized into two types, namely, ‘absolute experiment’ and ‘comparative
experiment’. If a researcher wishes to determine the impact of a chemical
fertilizer on the yield of a particular variety of rice crop, then it is known
as absolute experiment. Meanwhile, if the researcher wishes to determine the
impact of chemical fertilizer as compared to the impact of bio-fertilizer, then
the experiment is known as a comparative experiment.
10. Experimental Unit(s): Experimental units refer to the
pre-determined plots, characteristics or the blocks, to which different
treatments are applied. It is worth mentioning here that such experimental
units must be selected with great caution.
Tags : Research Methodology - Introduction
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