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Research paper : Modeling the social acceptance of industrial technologies (M. Matsumoto et al.)−26−Synthesiology - English edition Vol.2 No.1 (2009) (1) Products that contributed to countering global warming (reduction of CO2 emission)(2) Products purchased by general consumers.Specifically, they included energy-saving vehicles (hybrid cars etc.), energy-saving appliances (air conditioners, refrigerators, etc.), high-efficiency water heater, high-efficiency lighting, solar power generation system for home, and others.In terms of whose viewpoint the analysis should take, it was(3) Diffusion analysis useful to policymakers. The objectives of the survey were to answer the following questions.− To what level would the target eco-products diffuse at what speed?− What would be the effect on diffusion when subsidy is granted to the eco-product?− What would be the effect on diffusion if the energy-saving performance of the eco-product improves further in the future?We call the first question as basic analysis, and the following two questions as factor-change-effect or sensitivity analysis.(4) We develop a model that enables basic and sensitivity analyses.(5) We create an analysis tool so that analysis could be conducted readily.Finally, the period of diffusion analysis was set as follows:(6) Analysis would involve the long-term spanning several decades.While the first two points (target products) were determined at the beginning of the research, the following four points were unclear. It became apparent that clarifying the remaining four points was necessary in determining the appropriate model for the analysis. This will be addressed in chapter 4.3 Survey of existing modelsThe models for diffusion analysis of products can be roughly divided into two categories. One is logistic curve model (Bass model) and the other is consumer preference model. Their characteristics are described below. Also, learning curve model that describes the long-term price reduction of new technology is often used as model of technological and production innovations. The three models are described below.3.1 Bass model [4]-[6]Diffusion curve of a product often presents S-shape. Figure 1 shows the diffusion curves of major products in Japan. Frank Bass formulated the diffusion model by applying the logistic curve model, which was originally employed in physics and biology, to the dynamics of product diffusions[4].Mathematical formulation is as follows. When Xt is number of new purchases during period t, N is final number of diffusion, and nt is diffusion rate during period t (percentage against N), the equation will be as follows: Xt=( p+r・nt)・(1−nt)・ N (1)p is called coefficient of innovation and r is called the coefficient of imitation. In Fig. 1, N·nt is the vertical axis while Xt is the incline of the curve. Equation (1) can also be expressed as follows: −=( p+r・nt)・(1−nt) (2)When the boundary condition is set at nt=0=0, nt can be expressed as follows[2][6]: nt= (3)When the three parameters p, r, and N are determined, the temporal transitions of Xt and nt are determined.In applying the diffusion analysis to eco-products, in the 1980s, International Institute for Applied Systems Analysis (IIASA) of Europe used it for diffusion projection of renewable energy. While the Bass model could approximate the long-term temporal transition of diffusion, it was unable to analyze the effect on diffusion in case there were changes in the factors. For example, it was difficult to analyze the effect of product price changes due to subsidy policy on the diffusion, or the effect of change in consumer preferences on the diffusion. While attempts were made to incorporate the effects of price changes and advertisements to the model by extending the Bass model[5][6], it was only possible under assumption that sufficient statistical data were available.3.2 Consumer preference modelThere exists an approach of analyzing diffusion by constructing a model of consumers’ product preferencesNote 1). In the simple consumer preference model, hypothesis is set that Cell phonePCVTRColor TVCarAir conditionerWashing machine19551960196519701975198019851990199520002005020406080100Fig. 1 Diffusion transition curve for past major products.Vertical axis represents the household diffusion rate. Source: For items other than cell phones, Trend of Household Consumption – Annual Report of Consumption Trend Survey, Economic and Social Research Institute, Cabinet Office, Government of Japan. For cell phones, Report on Communication Usage Trend Survey for Households, Japan Ministry of Internal Affairs and Communication.1−e−(p+r)t1+r/p・e−(p+r)tdntdt

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