ABSTRACT
This chapter expands the discussion of data acquisition and exploratory data analysis to observational studies beyond the specific study site. Although the larger number of observations in regional data sets is an opportunity to conduct different and potentially more informative statistical analyses, an upfront warning on analysis of observational studies is in order: In the authors' experience, data preparation (assembly, cleanup, and quality control) is the single most time consuming part of using outside observational data. The objectives and design of a monitoring program determine its relevance to the case-specific investigation. Its technical foundation determines its quality. Evaluating the quality of biological assemblage data presents some unique challenges. The data typically consist of taxonomic names of species (or higher taxa) and estimates of abundance, such as counts of the number of individuals, biomass, or percent cover.
