In order to appraise a piece of medical literature, you need to ask questions to determine the study's validity, its importance, and its relevance to your patient. Validity in a research paper is indicated by clearly defined research questions, clarity in the methodology, blinding and randomization, reproducibility, for example. The type of study will determine the appraisal tool that is needed.
Here are some resources, including critical appraisal worksheets:
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