| The quality of life of people has been improving significantly with the extensive development of Chinese reform and open. However, because of the unsmooth information channel, the limited knowledge level and the bad mood, someone can not invest rationally in the stock market, which reflect the impetuous and anxiety. Among the many factors affected the investment decisions, if one changed, the investment decision would be affected radically. Therefore, the investment decision can be regarded as a complex system.This paper proposes a model on investment decision firstly. Through the analysis of the national ecological system and the investment decision ecological system, this paper illuminates their fit in theory, and then testify that the Lotka-Votera model can be applied to the study of stock investment decision. The mutual influence between rational and irrational investors will be analyzed through the Lotka-Votera model in this paper, with considering three relationships: competition, predation and reciprocity, and conclude that the main target is to achieve the coexistence equilibrium state. By choosing different parameters of the model, this paper analyzes the factors affected investment decision, and further analyzes their relationship by simulation. The financial crisis in 2008 is, as an example, to facility the result analyzed, and then offers some proposal about optimizing investment decision.The results indentify that the final destination of the investment decision is to achieve a balance of number of the rational and irrational investors, and they are in a coexistence state. If we wanted a rational investment decision, we should improve the number and growth rate of the rational investor to make the rational investors more than the irrational. Meanwhile, the influence of irrational investors should be improved as far as possible, reduce the negative influence of irrational investors as low as possible. Taking some measure, such as improving the policy, strengthening the propaganda, enforcing supervise and so on, to alter the interaction parameters and growth rate for investors, which can make the investment decision achieve the balance state rapidly andhave a better development of stock market. |
