Step 6: Revise and Rerun Screening (Optional)
Running a screening using the RPS Tool is often an iterative process. After viewing and assessing initial results, a screening can be rerun with updated subwatershed selections, indicator selections or weights. Users can carry out different variations on the original screening through quick and easy manipulations of the screening settings.
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Revisit the Screening Objective
It is not unusual for new users to begin with a very general screening objective, such as 'identify restorability differences' and refine or even change that objective as screening steps proceed. For example, a general screening objective such as 'identify and target the most restorable subwatersheds for restoration planning and implementation' might evolve into 'identify the subwatersheds that have good RPI Index scores as well as moderately high nutrient loads and target these for TMDL implementation.' A singular goal may also have transformed into multiple, more specific goals, such as 'target subwatersheds for Clean Water Act Section 319 nonpoint source projects that have impairments and a high Social Index score,' 'target subwatersheds with pathogen TMDLs and drinking water intakes for expedited restoration,' and 'target subwatersheds with impaired but restorable aquatic habitats for collaborative restoration with fisheries programs.' Because creating alternative screening runs is so easy, the RPS Tool can accommodate prioritization efforts with multiple screening objectives.
Some considerations for refining an initial screening include:
- Have the original screening purpose and desired end-products remained the same?
- Have new screening objectives emerged during the screening process?
- Do the subwatershed and indicator selections still align with the screening objective(s)?
- Do results of the initial screening provide meaningful insight into subwatershed differences?d
- Will additional screenings help achieve the desired end-products?
If these questions reveal additional screening needs, users can revisit earlier steps to refine and rerun their screening.
Integrate the Screening Runs
After conducting additional screening runs, users may have multiple versions of results that identify different sets of subwatersheds as potential priorities. There may be some degree of consistency in these results – with one or more subwatersheds scoring favorably even with variations in indicator selection and weights. Running multiple screenings can be informative but also challenging because users may want to distill the findings into a clear, cohesive end-product to inform decisions and actions. This is a project-specific task without a single, universal solution; nevertheless, the following approaches may be suitable:
- Select the preferred screening run. Refining iteratively and reaching consensus on a single preferred screening run may be preferable to integrating many screenings. Preferences can emerge when one (or very few) of the screening runs are clearly consistent with expert judgment and familiarity with the area being screened. Intensive discussions among project participants of preferred indicators that are strongly associated with the screening objective may also lead to confidence in just one screening. Selection of one specific screening run can further consider indicator data quality, validation of the results against reference sites and how well the screening run addresses the screening objectives.
- Integrate multiple screening runs if necessary.Should a user feel that no single run is ideal, they may consider integrating the results of the best runs available. Averaging or summing indicator scores of multiple runs are ways to combine results. Another approach could involve targeting subwatersheds that surpass a defined scoring threshold in any or all screenings (e.g., subwatersheds with top 25% Ecological Index scores across all five screening runs).
- Maintain multiple alternatives intentionally.Sometimes the most useful output is multiple sets of results rather than one. An assessment designed to assist a complex decision-making process, for example, might intentionally provide a few well-documented alternatives to decision-makers for their final action. Different screenings could also reflect contingency plans for different budget scenarios or different priority subwatershed selections for collaboration with different program partners. If a screening approach involved subsets of subwatersheds, such as separately screened lake versus stream subwatersheds, maintaining and using multiple sets of results can also be appropriate.