How are summaries of viability ratings calculated?

Ferreira,Catarina (elle, la | she, her) (ECCC)

• January 04, 2024 20:35

Hello,

Is there a specific article explaining the rules of rolling up the status of multiple indicators to produce one summary indicator status, based on viability assessments? I have found one for the threats rating but not for targets.

Thank you,

Catarina

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  Miradi Support

  • January 05, 2024 01:37

  Hi Catarina,

  Thanks for the question! We don't have an article in the Help Center describing these rules yet but we'll aim to publish it soon and we'll post an update here.

  One clarification to your question:

  As described in the Target Viability Assessment article, when conducting a simple target viability assessment, Miradi does not roll up the status of individual indicators to produce an overall target viability rating. When using simple viability mode, you must manually assign the target viability rating, and then update it manually as the status of your indicators changes.

  In contrast, when using the KEA-based mode to assess target viability, Miradi does roll up the status of individual indicators to produce a rating for each KEA, and then the KEA ratings are rolled up to generate the current viability status rating for the target. Note that the calculated status of KEAs is not displayed in Miradi Share, but it is displayed if you open your project file in Miradi Desktop.

  Based on your question, I am assuming you are looking for documentation on the roll-up rules for KEA-based viability assessments, but please correct me if I have misunderstood your question.

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  Ferreira,Catarina (elle, la | she, her) (ECCC)

  • January 05, 2024 14:40

  Thank you for the prompt reply. Indeed my question is related to documentation on the roll-up rules for KEA-based viability assessments, apologies for not being clear!!

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  Charles Latremouille

  • January 05, 2024 19:28

  Hi Catarina,

  The Miradi Desktop application does provide the rules for rolling up the status of multiple indicators to produce one summary indicator status based on viability assessments (see below). Hope this helps.

  Describe status of targets: 4) Record initial measurement

  Miradi will calculate a status rating for each KEA, based on the ratings of its indicators. The KEA ratings will be rolled up for each KEA type, and the average of the KEA type status ratings will be used as the viability status rating for the target (see below for calculation details). This target viability status rating will appear at the top of the properties dialog, and will be displayed in the diagram as a small oval next to the target.

  Hint:You must assign the type of indicator (size, condition, or landscape context) to each KEA for the roll-up algorithm to work.

  Miradi rolls up viability scores using an algorithm originally developed as part of the conservation action planning process of TNC. Each of the viability ranks has a numerical score associated with it:

  • Very Good = 4.0
  • Good = 3.5
  • Fair = 2.5
  • Poor = 1.0

  As TNC's process states, "This scale is a crude approximation of the underlying continuous viability scale. The non-linear numeric relationship among the viability classes reflects the diminishing return of moving up one class as one moves up the scale. For example, the viability score increases by 1.5 in moving from 'Poor' to 'Fair,' but only increases by 0.5 in moving from 'Good' to 'Very Good.'"

  The average viability score across multiple indicators for one target and for all focal conservation targets for the project site is calculated according to the following scale:

  • >= 3.75 = Very Good
  • 3.00 - 3.74 = Good
  • 1.75 - 2.99 = Fair
  • 1.75 = Poor

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