Step 5: Identifying probable causes for the Truckee River case study

1. Step 5: Identifying probable causes for the Truckee River case study

2. Detect or Suspect Biological Impairment Stressor Identification Define the Case List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Evaluate Data from Elsewhere Step 5: Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

3. Weighing the evidence for each candidate cause • Evaluate the quantity & quality of evidence • Evaluate consistency & credibility • Summarize the compelling evidence

4. Things to keep in mind when scoring… • Be consistent across candidate causes • Don’t double-count data • Think about the quality & quantity of the data you’re using • Document your thought process

5. R refutes D diagnoses +++ convincingly supports (or weakens - - -) ++ strongly supports (or weakens - -) + somewhat supports (or weakens - ) 0 neither supports nor weakens NE no evidence The scoring system

6. Let’s start scoring each type of evidence, across each candidate cause…

7. Evaluate quantity & quality of evidence • Quality & quantity of data influence scores • Now evaluate overall quality of evidence • Lots of consistent evidence reduces quality concerns for any 1 type of evidence • Poor quality data may be discounted • Consider study designs, methods, relevance, variability, & other QA issues

8. Now that we’ve scored each type of evidence, let’s evaluate consistency & credibility

9. Evaluate consistency & credibility • Prepare summary table of scores • Do not add up scores! • Evaluate consistency of evidence • Look for compelling evidence • If evidence is inconsistent, consider mechanistic explanations • e.g., lab data not consistent with field conditions due to differing bioavailability

10. Scoring consistency & credibility

11. Summarize compelling evidence • Make an overall evaluation of strength of evidence for each candidate cause • what evidence compels belief that candidate cause induced effect? • what evidence strongly casts doubt? • Consider the principle characteristics of causal relationships • these are what you’re trying to show • they summarize the 15 types of evidence

12. What comes after causal analysis? • If confidence in results is low… • plan studies to obtain critical evidence • experimental studies most likely to be convincing • If confidence in results is high… • identify sources • take action • monitor results

13. So – what’s next? • Additional data to collect? • Additional analyses to conduct? • Additional sites to consider? • Outreach & communication?