When searching for research evidence, consider that there is a hierarchy of evidence. The NCCMT Evidence-Informed Public Health website presents a pyramid of research evidence with different levels of evidence and provides the following guidance:
"Your search strategy should aim to locate the strongest quality and most relevant evidence first. When searching for quantitative evidence (e.g., effectiveness of an intervention, health effects, cost effectiveness, etc.) some study designs are considered stronger than others. It is important that the research design is the most appropriate to answer the question being asked."
Higher levels of evidence consist of syntheses of studies (e.g. systematic reviews) and summaries (practice guidelines). Bibliographic databases like Global Health, Ovid MEDLINE etc. will often include evidence syntheses and guidelines (in addition to individual studies), which can be easily retrieved by limiting your search results by publication type or study design. Databases that prioritize high-level evidence are sometimes referred to as evidence-based practice databases, some of which are available through the library (e.g. Cochrane Library) and others are freely available to search (e.g. Health Evidence).
Research databases often give you the choice of performing a basic or advanced search (note that most library databases accessed via Queen's University Library will default you to the advanced search).
A basic search can be incredibly helpful when looking for a few good articles on a topic or when you're doing some preliminary searching/work. However, a basic search is not recommended if your intention is to perform a comprehensive search. Furthermore, many search topics are complex and it can be to your benefit to use advanced search functionalities. When completing assignments with a literature search component, many instructors want to see evidence of an advanced search that demonstrates a deeper understanding of how databases work and function.
The following page works through search options available on Ovid. Ovid is a search interface/platform that is available for a number of different databases such as Global Health, MEDLINE, Embase, PsycINFO, etc. The examples and screenshots provided are from Ovid MEDLINE and may function or appear slightly different on other Ovid databases. Similar principles apply to other search platforms such as Ebsco for searching the CINAHL database.
Most databases will allow you to narrow your search results by applying limits. The options will vary by database but often include limits for publication date, publication types, age groups and language.