Observational: non-manipulative study design that typically represents realistic conditions. An example hypothesis: The prevalence of tomato pests will decrease if rain is sparse.
Experimental: Manipulative study design that alters a variable for comparison against a control condition. An example hypothesis: Transplanting tomato plants from field to greenhouse prior to fall will extend yield.
Explaining Terms
Meta-analyses and systematic reviews are types of observational studies while field trials are typically types of experimental studies. While many other study design types exist, these 3 common terms are defined below.
Definitions
Meta-analysis: A single article that systematically combines the data from published studies. All studies included previously aimed to address a specific and unifying question. Unlike systematic reviews, a meta-analysis uses statistical methods to quantify the summary results from the included studies. Because of this, many consider meta-analyses to be highly reputable.
Systematic Review: A single article that provides a comprehensive review and conclusion from previously published, relevant literature that meet certain inclusion/exclusion criteria established by study team.
Field Trials: Experiments comparing one treatment to another and implemented at several distinct locations to minimize bias contributed by different climates, soil quality, and pest types, etc.
