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Considerations for Optimal Monitoring Program Design
CASQA 9th Annual Conference, Squaw Valley, CA Monitoring Workshop September 9, 2013
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Design Challenges Size and complexity of MS4s
Spatial and temporal variability Ephemeral nature of many conditions Difficult sampling logistics More complex problems with interacting causes
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The Use and Abuse of QAPPs
99.99% of attention focused on sampling and lab methods 0.01% * of attention focused on Right questions? Right design to answer these questions? Right data analysis method? Does design meet requirements of data analyses? Do data analysis results actually address the questions? * Estimates accurate to +/ %
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Data Quality What is data quality? What are data quality objectives?
The ability of the study and its data to answer core questions What are data quality objectives? Characteristics of the data that ensure its ability to answer core questions
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Aspects of Data Quality
USEPA’s PARCCS construct Precision Accuracy Representativeness Completeness Comparability Sensitivity But even these are not enough Presume that already have goals, questions, appropriate designs
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Larger Context for Data Quality
All elements must be completed Elements must be coordinated Goals & questions of paramount importance Technical aspects driven by goals & questions
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Data Quality? Have conditions changed over time at Huntington Beach?
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How Much Do We Understand?
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Organizing Our Understanding
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The Right Amount of Complexity
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Collaborative Modeling
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The Tool Bag A wide range of approaches to choose from
Choice depends on state of knowledge, questions, logistics, time constraints, etc. No single right answer for all situations
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The Right Conceptual Model
Power analysis for regression of diazinon trends assuming steady decline over time Data courtesy of Alameda County
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Or, Maybe Not Power analysis for change in diazinon concentrations assuming a step-function decline Data courtesy of Alameda County
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Design Options Monitor all sites Monitor random subset of sites
Monitor only fixed trend sites Monitor only known problems Compare all data to standards Implement special studies Use hybrid designs
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Monitor All Sites Pros Comprehensive picture of conditions
Simple sampling strategy Track trends over time Cons Expensive and time consuming Lacks frame of reference for comparison
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Monitor Random Subset of Sites
Pros Statistically valid estimate of conditions Track trends in overall condition Design can be optimized for efficiency Cons May miss problem areas Unable to track trends at specific sites Lacks frame of reference for comparison
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Monitor Only Fixed Trend Sites
Pros Tracks trends over time Design can be optimized for efficiency Cons Does not describe overall conditions Lacks spatial frame of reference for comparison
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Monitor Only Known Problems
Pros Efficiently focuses monitoring effort Measures progress in solving problems Cons Does not describe overall conditions Lacks broader frame of reference for comparison
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Compare All Data to Standards
Pros Provides consistent basis for comparison Assesses compliance with regulations Cons Difficult to prioritize actions if exceedances widespread Standards may not provide meaningful action thresholds for local conditions
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Implement Special Studies
Pros Focus on specific issues Improve understanding More efficient Defined endpoint Cons Applicability may be limited May require specialized expertise
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Look at Deviations Bacteria in Aliso Creek Predictable patterns
Focus monitoring on subset of year Improved $$ and statistical efficiency of monitoring
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Control for Covariates
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Focus on Derived Variables
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Enterococci Aliso Creek: Exponential Regression
Drop in mean concentration over 11 years of 1 – 2 orders of magnitude Drop from mean of 2500 to 90
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Questions?
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