ESTIMATION OF EXISTENCE VALUES: SOME EMPIRICAL ISSUES
U A D P Gunawardena
Department of Forestry and Environmental Science
University of Sri Jayewardenapura
Existence values (EVs) are the values derived from the knowledge that
certain species or natural environments exist. Existence values are pure
public goods and hence lack market values. As income rise and natural
environment suffer greater degradation, demand for existence values is
likely to increase. This paper presents results of a contingent valuation
survey designed to elicit existence values of a tropical rain forest and
several issues related to estimation of existence values of a global resource.
A contingent valuation survey was carried out in order to derive EVs for
the Sinharaja Rain Forest Reserve in Sri Lanka. An open ended question
format was used with a neutral trust fund as a payment vehicle. Three
samples from Sri Lanka (urban and rural areas distant to the forest and
peripheral villages to the forest) and one remote sample (from UK) were
used in the study. The existence values for different types of users such
as educational users, recreational users and non users were derived from
When expressed as percentage of income, willingness to pay values showed
clear differences among different user types in different samples. On
average, local rural educational users stated the highest values while
remote non-users stated the lowest values. These existence value estimates,
notwithstanding the theoretical validity, clearly illustrate the empirical
problems related to estimation of existence values.
It could be assumed that existence values stated by non-users provide
the nearest approximation for the 'true' existence value of a resource.
However, this relates with the provision of information and the knowledge
of the respondent since people derive benefits directly and indirectly
and they may be aware or unaware of such benefits emanating from tropical
Implications of these findings in designing future existence
value estimations and the role of information in survey design are highlighted.
Implications for policy at global level, specifically, how mechanisms
for appropriation of such values could be developed are also discussed.