Why is a peer review necessary and what are its uses?
If you write an essay for publication in an academic journal, it will probably go for a peer review before it is published.
If you are interested in conducting a scientific research, you will probably have to go through the peer review process before your project is accepted.
A peer review may be instituted as a step taken before authorizing a grant; as a means of quality control, bid to improve standards; as part of an evaluation of an employee's performance or even to check what other experts feel about the viability of a plan before it is adopted for implementation.
Although there have been many critiques of the value of a peer review, it cannot be denied that the process has its benefits. When you are doing cutting edge research, require a grant so that you can work on a project, or even if you're a teacher who has instituted a new teaching method in your class, a peer-review helps the authorities measure--at least in part--the merits of your work.
A peer review can validate your ideas and make them creditable to the expert community of your subject. It can identify the lacunae in your research and suggest ways in which you may improve it. A peer review process may also bring forward duplications you may have inadvertently made or oversights in neglecting to include research that has already been conducted within the purview of your project.
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