'Critical evaluation' in reality may not be possible if you're not already at least fairly familiar with the field, and the kind of techniques used in the research. If you were working in the field and were thinking about trying to replicate the work, or build on it, generally the procedure is something like:<p>1) Read the abstract, to see if it's something you're interested in and willing to spend some time one. Reading the introduction will often help here as well.<p>2) Read the materials and methods section and attempt to reconstruct in your head or on a piece of paper exactly what the structure of the research was. If you're not familiar at least a little with the field this may be a rather difficult exercise, particularly if they use techniques you've never heard of. However, without going through this, you can't really do any critical evaluation of the research. This can be the most difficult part; understanding the techniques (and their various pitfalls etc.) may require reading other papers cited in the bibliography.<p>3) Read the results, and in particular, focus on the figures, which should correlate with the materials and methods section fairly well. Here look for things like error bars, statistics, clarity, etc. Poorly written papers tend to obfuscate more than enlighten. There should be good correspondence between materials and methods and results.<p>4) Finally, read the discussion. Overblown claims that don't seem supported by the results are not that uncommon, so retain a healthy sense of skepticism. A paper that discusses uncertainties in the results in an upfront manner is typically more reliable.<p>Thorougly evaluating a paper in this manner is quite a bit of work, and can take hours of effort, even by someone with actual research experience in the field.<p>Usually, if it was a field that you are not that familiar with (say as an undergraduate student or a new graduate student), you'd start not with research reports, but with published reviews of relatively recent work, which will give you an idea of what's mostly settled and where the controversies are. If you were completely starting from scratch, a well-regarded textbook could be a better option as an introduction.