Using Differential Model to Find the Best Time to Buy the IPhone

This research is important can help consumers find the best time to buy a new type of iPhone and help companies and manufacturers change their method to decide the price of their products. The data of the price and time are collected, and other variables like the market’s reaction are concerned. The main method is using a differential model that can find local minimums of the price curves of each kind of iPhone. All the variables are turned to a single one through building up functions. The result shows the time period between the end of the second month and the beginning of the fifth month is suitable for buying, and the fourth month is the best time. The suggestion for consumers is not to be too impatient to buy it. The suggestion for manufacturers is to produce and sell in a proper amount and price. The suggestion for market studiers is to build a similar or even better model to predict the price of similar products. Therefore, this research has great significance.