As mentioned elsewhere, filtered resources appraise the quality of studies and often make recommendations for practice. Sometimes, however, you will not be able to find an answer to your clinical question in such a resource and you will need to assess the evidence yourself—consider its validity, results and relevance.
Different publication types are appraised using different criteria. For example, an article about a therapeutic intervention would not be appraised using the same measures as an article about a prognostic indicator.
There are a number of checklists and tools available to help you appraise the evidence for various publication types:
Sheets are available for systematic reviews, diagnostics, prognosis and randomized controlled trials.
Checklists are available for systematic reviews, randomized controlled trials, diagnostics and more.
The TREND Statement (non-randomized trials)
University of Salford Health Care Practice R&D Unit Evaluation Tool (mixed methods studies)
While this course from Johns Hopkins is aimed at public health, it provides a broad overview of biostatistial methods and concepts, emphasizing interpretation and concepts rather than calculations or mathematical details. It develops the ability to read the scientific literature to critically evaluate study designs and methods of data analysis, and it introduces basic concepts of statistical inference, including hypothesis testing, p-values, and confidence intervals. Topics include comparisons of means and proportions; the normal distribution; regression and correlation; confounding; concepts of study design, including randomization, sample size, and power considerations; logistic regression, and an overview of some methods in survival analysis.