Table 1. Factors to Consider in Ecological Research.

Domain	Factors to Consider
Reasons to conduct ecological-level research	The research question is at a population level The theory used is at a macro level To identify groups or geographic units at high risk for an outcome Feasibility (ecological-level data are available and inexpensive to access)
Ability to make inferences	To the ecological level at which the study is conducted Be aware of: Ecological fallacy Ecological bias
Choice of unit guided by	Theory Maximization of intra-unit homogeneity Data availability Statistical power Be aware of: Change of support problem
Existing data particulars	May be readily or publicly available May be inexpensive to access May make study quicker to conduct Be aware of: Whether data quality varies between units collecting it Between-unit differences in processes used to measure a construct that may be mistaken as differences in the construct Whether measurement methodology or instrument changed over time Whether coverage or representativeness of data source matches intended ecological unit