Process and definitions

The data collection process

All information entered in MERMAID goes through validation before becoming live, scientifically valid data. When entering information from your dive sheets, whether online or offline, you work with transects and quadrats that are only visible to you, in the "Collecting" area of a project.

When you are online and ready to commit your observations, you validate each sample unit individually, and once all warnings and errors are addressed, submit it. Only then does the sample unit become visible to all project members in the "Submitted" area of the project. It is also part of all exported xlsx files, and available via authenticated mermaidr access. If the project's data sharing policy for that sample unit is not "private", the sample unit will also be available to non-project members, accessible via the MERMAID dashboard.


  • Site: A place, defined per-project as a unique set of latitude and longitude coordinates with a name and other attributes, where data is collected
  • Management Regime: A set of rules in effect at the time of data collection governing coral reef resources, with a name and other optional attributes.
  • Sample event: An episode of data collection occurring at a Site on a date, with a Management Regime in place. The unique combination of Site, date, and Management Regime defines a Sample Event, which is used for the aggregated calculation of sample unit-level survey results.
  • Sample unit: A group of observations collected as part of a particular survey protocol, at a given place on a given date (sample event). Because many survey protocols define a transect, "sample unit" is often used interchangably with "transect" but is more general, including, for example, collections of bleaching quadrats.
  • Observation: an individual measurement of an observable phenomenon collected as part of a sample unit, for example a benthic attribute at a point along a benthic Point Intercept Transect.
  • Validation: The MERMAID online process all sample units must undergo before becoming scientifically valid data.
  • Error: a validation issue prohibiting submission because it violates fundamental survey protocol definitions; for example, a transect cannot be submitted without a defined length.
  • Warning: a validation issue that flags an unusual value, such as a fish size greater than previously recorded. Warnings can be addressed by changing the relevant value or by indicating that the warning should be ignored.