5.1　Influence of Natural Disasters

Haiti is a country full of natural disasters and many major natural disasters in the history have caused a huge impact on its development.It is quite necessary to take the impact of natural disasters into consideration and thus we revise the model as follows：

Of whichδit represents the intensity of natural disasters in the year t.Inδit～N,S 2),is the average intensity of natural disasters in the history of Haiti and S 2 is the statistical variance of the intensity of natural disasters in the history.μ represents the national capacity of handling natural disasters,and the higherμis,the less the natural disasters affect the indicators.In fact,the national capacity is gradually increasing.In order to simplify the problem,we makeμ=0.5.