Quasi experimental design (1)

Quasi experimental design (1)

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  QUASI EXPERIMENTAL RESEARCH DESIGN Mr. VipinPatidar Asst. Prof. K J Institute of Nursing, Vadasma
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  INTRODUCTION • Quasi experimentalresearch design involves the manipulation of independent variable to observe the effect on dependent variable. • The study unlike true experimental study lacks at least one of the three cardinal characteristic (Randomization, Control)
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  • Quasi experimentaldesigns have an element of manipulation. • Quasi experimental designs are generally used to establish the causality (effect of independent variable on dependent variable) in situations where researchers are not able to randomly assign the subjects to groups for various reasons.
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  CHARACTERISTICS • Manipulation ofthe independent variable to observe the effects of the dependent variables. • It lacks at least one of the two other essential characteristics of the true experiment.
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  • Quasi independentvariables are used instead of true independent variables and independent variable is not manipulated in complete controlled situations.
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  TYPES There are severaltypes. The two important types are as follows: 1. NON RANDOMIZED CONTROL GROUP DESIGN. 2. TIME SERIES DESIGN
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  NON RANDOMIZED CONTROL DESIGN •Is also known as “non equivalent control group design”. • This design is identical to the pre test- post test group design, except there is no random assignment of the study subjects in experimental and control groups.
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  • In thisdesign experimental and control groups are selected without randomization. • Dependent variables are observed in experimental as well as control groups before the intervention.
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  • Later theexperimental group receives treatment, following which the post test observation of dependent variable is carried out for both the groups to assess the effect of the intervention or treatment on experimental group.
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  NON RANDOMIZED CONTROL GROUPDESIGN CONTROL GROUP PRE TEST TREATMENTEXP GROUP PRE TEST POST TEST POST TEST
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  TIME SERIES DESIGN •Time series design is useful when the researcher intends to measure the effects of a treatment over a long period of time. • The researcher would to continue to administer the treatment and measure the effects a number of times during the course of the experiment.
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  • In asingle - subject research, in which the researcher carries out an experiment on an individual or on a small number of individuals, ……..by alternating between administering and then withdrawing the treatment to determine the effectiveness of the intervention.
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  TIME SERIES DESIGN EXPGROUP O2O1 O2 O3 O1 O3TREATMENT
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  EXAMPLE • Measurement ofa learner’s performance in a college on weekly basis and then introducing a new teaching technique. Then again measuring on weekly basis.
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  ADVANTAGES • Quasi experimentaldesigns are more frequently used because they are more practical and feasible to conduct research. • Where the sample size is small, and where randomization & availability of control group is not possible, this design is preferred.
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  • Quasi experimentaldesign is more suitable for real natural world setting than true experimental designs. • This design allows the researchers to evaluate the impact of quasi independent variables under naturally occurring conditions. • In some cases hypotheses are practically answered through this design.
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  DISADVANTAGES • In thisdesign there is no control over extraneous variables influencing the dependent variable. • The absence of a control group and absence of control over the research setting makes the result of this design less reliable and weak for the establishment of causal relationship between independent & dependent variable.
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