Strengths and Weaknesses of Non-monetary Indices
Strengths
¥Can focus on necessary conditions to provide services
¥Can be based on conventional tool of the production function
¥Can reflect factors that determine aggregate willingness to pay
¥Can reflect risks of service flow disruptions 
¥Can be site-based and take account of landscape context
¥Can be used as benefit-transfer method if $$ estimates exist
¥Can be used to compare environmental assets for trading
¥Can be used for prioritizing environmental investments
¥Similar to indicators that decision-makers use everywhere else
¥Practical because of GIS and Web
¥Can reflect relative preferences for mix of services

Weaknesses
¥Cannot be used in conventional benefit-cost analysis
¥Not very useful for justifying increases in levels of $ spending
¥Generally unpopular with economists, scientists, & policymakers
¥Requires some decisions that will appear to be arbitrary
¥Requires acceptance as better than $$ and better than nothing
¥Requires upfront investments in data collection/software