Sampling Units and Project Hierarchy

This page defines what a sampling unit is and helps explain how to think about them in a hierarchical structure in Point Blue’s database.

What is a sampling unit?

A sampling unit is a named location(s) where you make observations in the field, such as transects, area search plots, nets. Sampling Units can contain other, smaller Sampling Units; giving you a way of organizing your project logically and spatially.

A project hierarchy is described below using a fictitious example called the State Monitoring Network.

1. Project or Sampling Unit: This project is called the State Monitoring Network. The project covers the geographic area of California.

2. Area Survey Locations (sampling units): The State Monitoring Network has unique areas that are labeled as sampling units. They are called Site 1, Site 2, and Site3. They represent 3 properties that are monitored in the State Monitoring Network. This project decided to make these sampling units so the data can be categorized easily at this level.

3. Survey Types: In this project, we are using two main survey types: Area Search and Point Count Surveys. Each Site can have as many Survey Types as you need. The most survey types used at one site in this example is two, for Site 3.

4. Individual Survey Events: There are three types of protocols used in the State Monitoring Network. At Site 1 they collect Point Count data, which are located along a transect. At Site 2 they collect Area Search data. Note that all Area Search polygons are smaller and within the Site 2 area. At Site 3 there are two survey types being used. One is Area Search and the other is a type of Transect which is comprised of 3 Secretive Marsh Bird Surveys.

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