別紙様式８研

究

主論

文抄

録

論文題目
Stated choice valuation of non-market environmental goods: Considering complex decisions andheterogeneity（意志決定のプロセスと選好異質性を考慮した非市場環境財の選好意識データによる価値評価法）
熊本大学大学院自然科学研究科（論文提出者

環境共生科学専攻

主任指導

溝上章志教授人間環境工学講座）

Parumog Michelle Gan（パルモグミッシェルガン）主論文要旨
This thesis is about non-market environmental valuation choices that do not follow conventionalrationality assumption. We present here a collection of essays on issues surrounding theenvironmental valuation allowing for complexity and heterogeneity in decision-making ofindividuals. Implications of these decisions are important in task of ensuring sustainable global
and local environment policies. Stated choices have been important basis of these environmentalvalues. Stated choices are responses in hypothetical choice questions. Unlike revealed
preference data, or actual choices from actual options, stated choices are more complex as actualexperience of the situation posed is not present. This is commonly analyzed though utility
maximization discrete choice method which assumes a ‘rational’ man maximizing his utility
over a set of alternatives. In this thesis, we show that an individual, when stating preferences
about environment state alternatives, is far from ‘rational’. Aspects out of the conventional
utility function influence his decisions. External factors such as questionnaire design andresource characterization and internal factors related to psychological status of an individual orpreference heterogeneity of samples are some factors that adds complexity to analysis.

Stated-choice valuation can be worked in discrete elicitation format like in referendum
contingent valuation (CV) or choice from a set of alternatives with varying environmental
attributes. The analytical foundation for these valuation formats is generally based on neoclassic
welfare analysis. As ecological behaviour is widely acknowledged to be influenced by beliefs,
attitudes, perceptions and motivations, it is unlikely that a homogeneous group of rational
choice makers can be achieved. This thesis is concerned with summarising and proposing
extensions on models used to analyze discrete environmental valuation data to account for
irrationalities and uncertainties in choices.
The research focus on two stated-choice valuation methods: CVM and attribute-basestated-choice method (ABSCM). Many researchers have raised questions on the reliability ofwillingness to pay (WTP) estimates from these models as affected by context design,psychometric bias, and tastes variations. This thesis initially presents a general framework fordiscrete choice analysis involving stated-choice experiment on environmental premiums. It thenpresent behavioural construct, formulate analytical framework and empirically demonstrate theproposed model extensions. Multinomial probit and logit models assimilating bounded andunbounded distributions are conventionally used in discrete stated choice valuation methods.
The sources of irrationalities and uncertainties, and the model improvements we propose arediscussed below.
Response effects- These models are based on referendum CV format. The inconsistencies ofindividual responses are affected by the survey design, bid cues, and the inherent strategic
behaviour of respondents. These can be addressed by assuming flexible error structure, latentvariables, and strategic scaling in utility maximization.
Tasks complexity in perceiving goods dimension - Environmental and natural resources can bemeasured in terms of quality, quantity, or a measure of both. However, the perceiving thedifference may be difficult in stated preference experiments due to goods nature and theindividual’s lack of experience of the good in real market. Here, we present two methodologicalframework and empirical demonstration to address them. One considering correlation inresiduals of different scenario context and the other presenting attribute base representation ofgoods component where attribute level prices can be directly measured. We present here amodel considering the limited information-processing capacity of individuals.
Difference in perceptions of environmental level and attitudes - Perceptions and attitudes areinvestigated be factor that contributes to variance of willingness-to-pay for environmentalimprovements. The latent indicators of these factors are investigated and integrated in themodeling though incorporation of covariate in the variables related to good or its attribute level.
Heterogeneity - Taste heterogeneity is brought about by inherent differences in individuals
brought about by a combination of different factors. Computational advances can now
accommodate random coefficient models with different correlation structure. Differentspecification these models were investigated to investigate which model specification is best forenvironmental valuation.
The data used in the empirical demonstrations are: 1) CVM data on the valuation of damage tocultural heritage site by a road project in Cebu City, Philippines; 2) CVM data on the valuationof Aso National Park, Kumamoto, Japan; and 3) ABSCM data on measuring traffic externalities
value of private and public work trips in Metro Manila, Philippines.