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  2. Causal Analysis/Diagnosis Decision Information System (CADDIS)

Estimating Taxon-Environment Relationships: Central Tendencies

  • Introduction
  • Using Taxon-Environment Relationships
  • Estimating Taxon-Environment Relationships
  • Computing Inferences
  • R Scripts

Central Tendencies

Helpful Links
Topics In Estimating Taxon-Environment Relationships
  • Overview
  • Data Requirements
  • Central Tendencies
  • Environmental Limits
  • Parametric Regressions
  • Non-Parametric Regressions
  • Assessing Model Fit
  • Measurement Error
  • Survey Weighting
  • Placing Taxa into Tolerance Categories
Other Pages And Websites
  • Using R to Estimate Central Tendencies
  • Weighted Average Inferences

PECBO Appendix Site Map

Taxon-environment relationships can be expressed in terms of central tendencies that describe the average environmental conditions under which a taxon is likely to occur. Using this method, the single-value descriptor of the taxon-environment relationship, uwa, for taxon j is estimated by computing the mean of the environmental variable of interest at the sites in which the taxon is observed:

EQUATION 1
EQUATION 1
where N is the total number of sites and xi  is the value of the environmental variable of interest at site i. For presence/absence data, Yij  is equal to 1 when taxon j is present at site i and 0 when taxon j is absent. For abundance data, Yij  is the abundance of taxon j at site i. Statistical scripts for computing central tendencies are available under the R Scripts tab of this section.
 
Once central tendencies are computed for each taxon, one can use them to infer conditions at a new site based only on biological observations, by computing a weighted average inference.

Causal Analysis/Diagnosis Decision Information System (CADDIS)

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  • Volume 1: Stressor Identification
    • About Causal Assessment
    • Getting Started
    • Step 1. Define the Case
    • Step 2. List Candidate Causes
    • Step 3. Evaluate Data from the Case
    • Step 4. Evaluate Data from Elsewhere
    • Step 5. Identify Probable Causes
  • Volume 2: Sources, Stressors and Responses
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  • Volume 4: Data Analysis
    • Selecting an Analysis Approach
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    • Basic Principles & Issues
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  • Volume 5: Causal Databases
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Last updated on February 13, 2025
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