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Frequent Questions about CADDIS

Illustration of a caddisfly which is representative of the CADDIS website.

Who should use CADDIS?

The CADDIS site contains technical information and was designed for use by scientists and engineers. However, much of the information on CADDIS may be useful for a wider audience as well, for example, Volume 2 provides background information on common sources and stressors.


How do I use the CADDIS site?

CADDIS is a website designed to help users conduct causal assessments. It is organized into five volumes, each with distinct content & tools. If you are new to causal assessment, we recommend that you first review the information in "Getting Started" in Volume 1, which includes a guide overview of the SI process described on the CADDIS site. Once you are familiar with causal assessment and the CADDIS site, you can move between volumes however you like, to view the information most helpful for answering your specific causal assessment questions.


How much data do I need to use CADDIS?

The Stressor Identification process outlined on CADDIS does not require a minimum data set, and existing data often are sufficient to determine the cause of an impairment. We recommend you review the section on Getting Started with data analysis to help you develop a sound foundation for your analysis. If the available data are too sparse to support a causal analysis, it may still be useful to go through the Stressor Identification process, but at a screening level, with the objective of identifying the data that would be most fruitful to collect. In addition, an important part of the process is evaluating whether the data used are of sufficient quantity and quality to support the causal analysis.

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How has CADDIS been updated in the 2017 release?

In July 2017, EPA launched a new revision to the entire CADDIS website as it was migrated to the Agency's Web Content Management System (WCMS), using Drupal software. This new version of the site has volume specific navigation with links back to the main entrance to the site, an integrated search function and a common glossary. Seasoned visitors should be familiar with the layout of the volumes and content and new users should be able to find CADDIS materials easily. Back in 2010, we released an update to the CADDIS site that included new content in each part of the site, with the reorganization of the five volumes, or topic areas. Listed below are those volumes, and the new content within each volume.

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Can I use CADDIS to determine causes of biological impairment in ecosystems other than streams?

Yes. The Stressor Identification process (and, by extension, the process outlined in the Step-by-Step Guide) is a general method for analyzing causes of detrimental biological effects. To date, the process primarily has been used for evaluating causal relationships in stream ecosystems.

However, because it is based on fundamental principles of causal analysis, the process should be useful for causal assessments in any ecological system, and case studies have been completed in terrestrial systems.


Can I use CADDIS to identify the source of a stressor causing biological impairment?

Yes. CADDIS will help you identify the stressor that is contacting or co-occurring with aquatic organisms in a way that causes detrimental changes. Identifying the sources of those stressors, developing and implementing management options, and monitoring restoration effectiveness are all important activities that technically are outside the scope of the CADDIS site.

However, accurate and defensible identification of the cause is the key that directs management efforts toward finding solutions that have the best chance for improving biological condition, and the logic framework and tools provided on CADDIS can in some instances be applied to the source-to-stressor portion of the causal pathway.


Can I print out all or portions of the CADDIS site?

Yes. You can print out individual pages in CADDIS using the print function on your web browser, and throughout the site certain sections may be available as separate PDF files (e.g., the Urbanization module, conceptual diagrams, etc.). The SI guidance is also available for download and printing.

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What are the differences between causal analysis, the Stressor Identification (SI) process, and CADDIS?

A "cause" is something that brings about an effect or result. The "analysis of causal relationships" is central to everyday life and science, and it identifies the means by which we can improve our environment. The Stressor Identification (SI) Guidance Document provides a formal and rigorous process for identifying the stressors causing detrimental biological changes in aquatic ecosystems. The SI approach is based on three methods for evaluating causal relationships: refutation, diagnosis, and comparison of strength of evidence. CADDIS uses these three methods, but in a more integrated manner, and it emphasizes a step-by-step process for assembling and evaluating evidence.

CADDIS also contains additional tools and resources to help in conducting causal assessments, as well as clarifications and updates developed since the SI Guidance Document was published.

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