Wednesday, June 22, 2016

Quasi experimental research

Quasi experimental research
It involves manipulation of an independent variable, lacks either the randomization or control group features.
Types
There are two types most commonly used in nursing research;
1. Non equivalent control group design
2. Time series design
  • Non equivalent control group design
It involves a treatment and two or more groups of subjects observed before and after its implementation. This design is useful, where the researcher is not able to do randomization due to unavoidable ethical reasons. This design is weak without randomization. On the other hand, the design is strong due to collection of pretest data allows us to determine whether the groups had similar morale initially by collecting pretest data, if the two groups are comparable with regard to demographic variables, the researcher could be relatively confident that any post test difference is self reported morale was the result of experimental treatment.
  • Time series design
It involves the collection of data over an extended time period and introduction of treatment during that period. The researcher is able to collect measures of outcome variables before the intervention, during the intervention, after a period of intervention and so on.
Advantages of quasi experimental research
It seems to be more practical than the experimental designs. Nursing researchers conduct studies in natural settings, where it is unethical to deliver an innovative treatment to a cluster of people through randomization.
Disadvantages of quasi experimental research
With these types of experiments, there are alternative explanations for observed results. A researcher wants to evaluate the effectiveness of weight gain among infants, if there is no comparison group to observe weight gain, one can easily ask question that: Is the weight gain among infants would have occurred without intervention? These types of questions called as rival hypothesis. If the answer is yes, inferences about treatment effectiveness are weakened.
In research reports, the researcher does not mention regarding random assignment or comparison group, probably it is safe to conclude that the design is quasi experimental and pre experimental.

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