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You can still access the UC Berkeley Library’s services and resources during the closure. Here’s how.
What is evidence?
All research is (potentially) "evidence" and there are no "perfect" studies.
Critically evaluating what you read will help any unearth biases or methodological shortcomings that may be present.
Is there an agenda (bias)?
It's doubtful that any study of humans is without some kind of bias, either in the study design, or in the author's pre-existing beliefs. How bias in methodology was controlled and the significance of bias in any particular study is what's relevant.
Things to consider:
The question being addressed: What kind of research gets funded?