Examples of hierarchical datasets

Often, many different types of observed data lend themselves to hierarchical models. Below are six examples of data that were analyzed using mixed-effect regressions. In this case, the term mixed-effect regression is used because this variation of the term hierarchical model was used in all of these studies.

• A study where molluscs were exposed to pollution, grouped by tank with the same number of individuals per tank.
• Examining vehicular crash data in Virginia, USA, using data from different counties (regions) that vary in population.
• Kidney disease studied through time, where multiple observations were recorded per individual.
• Land value modeled using data on multiple spatial scales.
• Modeling county-level opioid-related deaths, accounting for differences in counties using a mixed-effect regression.
• Variation in bike routes estimated by tracking individuals through time using GPS.