Research Design: Concept and Importance in Research

 Before describing the different research designs, it will be appropriate to explain the various concepts
relating to designs so that these may be better and easily understood.

1. Dependent and independent variables in research

In research, variables are any characteristics that can take on different values. For example, height, age, temperature, and test scores are all variables.

Dependent and independent variables are two types of variables that are often used in research to test cause-and-effect relationships.

Independent variables are the variables that are manipulated or controlled by the researcher. They are the variables that are thought to cause a change in the dependent variable.

Dependent variables are the variables that are measured or observed by the researcher. They are the variables that are thought to be affected by the independent variable.

For example, if a researcher is studying the effects of caffeine on test scores, caffeine would be the independent variable and test scores would be the dependent variable. The researcher would manipulate the caffeine level (e.g., give participants different amounts of caffeine) and measure the change in test scores.

Another example: if a researcher is studying the effects of exercise on weight loss, exercise would be the independent variable and weight loss would be the dependent variable. The researcher would manipulate the amount of exercise (e.g., have participants exercise for different duration's of time) and measure the change in weight.

2. An extraneous variable is any variable not being investigated that has the potential to affect the outcome of a research study. In other words, it is any factor not considered an independent variable that can affect the dependent variables or controlled conditions

3. Control: One important characteristic of a good research design is to minimize the influence or effect of extraneous variable(s). The technical term ‘control’ is used when we design the study minimizing the effects of extraneous independent variables. In experimental researches, the term ‘control’ is used to refer to restrain experimental conditions.

4. Confounded relationship: When the dependent variable is not free from the influence of extraneous variable(s), the relationship between the dependent and independent variables is said to be confounded by an extraneous variable(s).

5. Research hypothesis: When a prediction or a hypothesised relationship is to be tested by scientific methods, it is termed as research hypothesis. The research hypothesis is a predictive statement that
relates an independent variable to a dependent variable. Usually a research hypothesis must contain,
at least, one independent and one dependent variable. Predictive statements which are not to be objectively verified or the relationships that are assumed but not to be tested, are not termed research hypotheses

6. Experimental and non-experimental hypothesis-testing research

When the purpose of research is to test a research hypothesis, it is termed as hypothesis-testing research. It can be of the experimental design or of the non-experimental design. Research in which the independent variable is manipulated is termed ‘experimental hypothesis-testing research’ and a research in which an
independent variable is not manipulated is called ‘non-experimental hypothesis-testing research’.

 7.  Experimental and control groups: 

In an experimental hypothesis-testing research when a group is exposed to usual conditions, it is termed a ‘control group’, but when the group is exposed to some novel or special condition, it is termed an ‘experimental group’.

 8. Treatments: The different conditions under which experimental and control groups are put are
usually referred to as ‘treatments’.

 9. Experiment: The process of examining the truth of a statistical hypothesis, relating to some research problem, is known as an experiment.

10. Experimental unit(s): The pre-determined plots or the blocks, where different treatments are
used, are known as experimental units. Such experimental units must be selected (defined) very
carefully.