The researchers and reviewers are known to each other, this type of review is believed to reduce plagiarism, however, there is the concern criticisms are watered down, either due to politeness or worried about the retribution the reviewer may face
The researchers name is not released to the reviewer. With it being anonymously reviewed, it is hoped it will it will be an unbiased review, however, this is often not the case and the reviewer can sometimes hide behind their anonymity and be undeservedly harsh
Both the researcher and the reviewer are anonymous to each other, this will mean the review is free from bias, however, often the researcher is identifiable by their writing and research style
Peer reviews are not unbiased, this is because the research world is relatively small and so researchers and research is known by most within that social world. Another reason it is often not unbiased, is the idea that researchers are funded by different organisations who want certain research deemed acceptable and push for that to happen
It is also felt the ability to publish research is in the control of the elites and that they do not like change or revolutionary ideas, so, they reject research which is not agreed with