2005 年 32 巻 1 号 p. 29-54
In the current consumer's market, for most products there are a number of brands to choose from. However, the number of brands contained in the choice set is usually very small and it is approximately two to five in number. Taking this point into consideration, it becomes very important for each company to strategize how to place their products into the consumer's choice set in order to expand its market share.
To solve this issue, many studies regarding the choice set have been done in the preceding studies. In particular, the Moriguchi model (1996) has the feature such that the model is built based on the nested logit model. However, the number of alternatives available for the model is limited and the model has some weak points. After that, Sakamaki (2003) proposed an improved model against Moriguchi (1996) model. Sakamaki (2003) model has the feature such that we categorize the alternatives, and we can know the effect of choice set on category level. However, we cannot know the effect on alternative level. In this paper, we try to clarify the weak points of both of these models, and propose an improving choice set model in which we can know the approximate effect of choice set on alternative level even if there are many alternatives, based on nested logit model.
We will use HII model (Hierarchical Information Integration model) for our improvement. In the preceding studies, HII model is used only for the study of conjoint measurement analysis to use many attributes in the model. In this sense, our study also includes the development of HII model from attribute level to alternative level.
Moreover we apply questionnaire survey data to our model and verify the appropriateness of our proposal.
