Improving the method of alternatives analysis 13 May, 2016 Tetsuya Kamijo JICA Research Institute, Tokyo, Japan at IAIA16, Nagoya, Japan

Introduction The discussion of alternatives is “the heart of the EIS” (CEQ 1978). Despite its importance, little progress on alternative considerations has been observed over years (Geneletti 2014). The study aimed at better understanding the actual discussion of alternatives and improving the method of alternatives analysis.

Second Mekong (Tsubasa) bridge in Cambodia Completed in April 2015

Discussion of alternatives Four alternatives (no action, ferry improvement, bridge construction, ferry improvement plus bridge construction) and 13 evaluation criteria using AHP Three times of discussion (October and December of 2004, and March 2005) Result: ferry plus bridge (.480), bridge (.234), ferry (.191), and no action (.095) Local people appeared to show little interest in alternatives.

A result of AHP

Principal component analysis (PCA) The PCA is a popular multi-variable analysis and transforms a number of correlated variables into a small number of uncorrelated variables (principal components: PCs); Two of three PCs visualizes the merits and demerits of alternatives on a scatter diagram, and shows a preferable option; and The PCA has merits of reducing a number of evaluation criteria and avoiding high correlations between them.

Result of PCA

Summary of PCA The cumulative contribution rate (CCR) of two PCs was .95, which was very satisfactory. The PC scores showed that the option of ferry plus bridge had merits compared to other three options. The 12 criteria except resettlement was very high and seemed to be transformed into the first PC.

Discussion 1 Comparison of AHP and PCA The AHP showed an order of options with scores but didn’t show merits and demerits of options. The PCA reduced 13 criteria to two PCs and avoided high correlations, which might be easier to understand comparison of options. The PCA may be a simple and objective method of alternatives analysis.

Discussion 2 Selecting suitable alternatives and evaluation criteria The PCA could facilitate selection of alternatives and criteria. The tentative alternatives and criteria could be corrected while watching results of PCA. Alternatives and criteria transformed into three PCs such as environment, development, and society could be one answer.

Conclusion The PCA may be one simple and objective method. The PCA is a typical statistical method and its use is easy. Further research is needed to verify its effectiveness via more case studies.

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