• Research articles– “Primary literature” where scientists present findings from experiments they performed.
  • This is the bread and butter of scientific publications, what you typically think about when you hear “scientific article”
  • Look for experimental methods and figures showing experimental data (graphs, plots, gels, etc.)
• Review articles – scientists collate, synthesize, & tell you about the work of multiple *other* groups of scientists.
  • Narrative review articles – scientists survey the literature, choose which papers they want to incorporate, then write a narrative piece telling you about their (subjective) take on the current state of the field. 
  • Systematic reviews – these are more objective (though remember garbage in, garbage out!!) reviews trying to determine and report a “consensus” from multiple studies – scientists use predefined criteria to mine the literature and select papers to include the results of. 
    • In a meta-analysis, they pool results from different studies and do fancy statistics on them.

Other types of articles you might come across:

• Article reviews – These are given different names depending on the journal they’re published in (Perspectives/Commentaries/News & Views, etc.), but they have in common that they’re highlighting the results of a recently published research article (or articles). 
  • These can be a great place to learn about new papers as well as to help you understand the denser research article. 
  • These are more technical than “general audience” coverage of the articles, but a nice “in-between”
  • Often put the new research critically into a broader perspective.
• Methods papers – scientists tell you how they developed a cool new method and give some proof-of-concept examples of uses (but the highlight is on the method itself, not the findings made using the method)
• Protocols papers – scientists take you step by step through how to perform an experiment
• Primers – narrative review-type articles that focus on helping scientists learn about a field, subfield, and/or technique outside their subject expertise
• Theory papers – scientists explain theories they’ve developed, but they don’t do experiments to test them.
• Clinical trial results – scientists present results of pre-registered clinical trials. “Gold standard” is typically a randomized controlled trial (RCT) in which patients are randomly given one treatment or another treatment or a placebo and then their outcomes are compared. 
• Case reports/studies – doctors present “odd” or “unusual” findings or report on the treatment of a single patient using a non-conventional strategy.
• Case series – doctors present findings from multiple similar case reports of. These may provide impetus for larger, more official, studies