According to different literatures, it seems like many factors could determine housing bubble and many methods could indicate size of housing bubble. For the definition, real-estate bubble mainly refers to price of housing is extremely high and is further away from fundamental value. According to the definition, the size of housing bubble= current price minus fundamental value. There is no official formula to calculate fundamental value until today. Some studies adopt regression analysis in tracking the bubble phenomenon. They quantify housing price bubbles by comparing the fundamental and the actual housing prices though there are some drawbacks. The most important defect is that each regression analysis requires unique assumptions on market-based
