Showing posts with label quantitative methods. Show all posts
Showing posts with label quantitative methods. Show all posts

Saturday, January 23, 2010

Quantitative Assessment of House Price Distributions

This weekend, as I found myself inundated in quantitative finance problem sets, I decided it might be worthwhile to apply some quant methods to real estate. After all, we're in the midst of a recession whose numerous causes - and/or exacerbating factors - include a multi-year decline in median home prices across virtually every geographical market. Furthermore, a larger proportion of Americans own a home than own equity securities. My experiment began with market selection; I wanted to compare two housing markets within relative geographical proximity. I also wanted the comparison to be between markets that have suffered comparably during the recession, and are perceived as good long-term housing bets for reasons such as population and demographic trends, weather etc. After brief deliberation, I decided that tonight's matchup would be between Atlanta and Charlotte.

To begin, I pulled data from the S&P Case-Shiller Home Price Index (monthly) from January 2000 to October 2009. I then converted the index value to a periodic rate of return for each month, using the natural log function. That data was then summarized in histogram format below:

 
The two distributions are somewhat similar at first glance, although Atlanta appears more skewed to the left. Atlanta's most frequently observed interval (bin) of return is also a bit higher than Charlotte's. However, in this instance I'm most interested in providing an investor with a general idea concerning the risk associated with a house purchase in each of these markets. To do so, I computed the mean and standard deviation for each city's returns. Furthermore, I calculated the (theoretical of course) probability that a given month's return would be less than zero for each market:

The Conclusion: Although the monthly return could conceivably be higher for an Atlanta house, there is a 45.75% probability that a given month's return will be less than zero - negative that is. In Charlotte, that figure is only 39.54%. Furthermore, it's important to note that the Atlanta data is characterized by a fatter left tail; that is, Atlanta has experienced multiple months of >2% price declines, while Charlotte's returns all fall above -2%.

Clearly, there are many variables that influence house prices, not all of which are even subject to attempted forecasting. However, I would venture to say that the method above provides a reasonable illustration of the relative risk associated with a real estate investment in the two subject markets.

*no positions in either Charlotte or Atlanta real estate. I am licensed to sell real estate in NC however. Sphere: Related Content