Saturday, January 30, 2010
How Canada Avoided the Financial Bubble
Tuesday, January 26, 2010
History Repeating: 1937
Science as System
Sunday, January 24, 2010
The Three-legged Health Care Stool

Wednesday, January 20, 2010
Mr. Brown Goes to Washington
Tuesday, January 19, 2010
A Cold North Wind for Neoliberalism
"I can be very frank about it: What we want to do is abolish this neo-liberal greed philosophy that was driving things in the bubble years," he says. "What we want to re-establish in Iceland is a strong Nordic welfare society with equal justice and equality."
A Framework for Policy
Thursday, January 14, 2010
What is the Individual Mandate?
Wednesday, January 13, 2010
Wall Street High Rollers on Capital Hill
Today, before the Financial Crisis Inquiry Commission, J. P. Morgan CEO Jaime Dimon and other Wall Street Barons testified about their role in the financial crisis. A few days ago, Mr. Dimon commented that J. P. Morgan's operations are run for clients and "it is not a casino." Although Mr. Dimon tempered his comments a bit before the Committee, me thinks he doth protest too much.
Monday, January 11, 2010
A Random Walk Among the Undead

A forecast with this model (displayed above) shows that our best prediction for the future of S&P 500 prices is the current price, as called for by the random walk hypothesis. Actually, the forecast above was not made with a pure random walk model but rather a random walk with drift model. The pure random walk equation is X(t) = X(t-1) + e(t-1) where e(t-1) is random, uncorrelated error. The random walk with drift is X(t) = a + X(t-1) + e(t-1) where a is the drift term. Supposedly, the drift term invalidates the random walk hypothesis, but even with drift the market is not very predictable.
Funding Health Care Reform by Taxing "Cadillac" Health Plans
Thursday, January 7, 2010
Failing to Connect the Dots
Wednesday, January 6, 2010
Double Bubble, Toil and Trouble
In an earlier post I showed how feather forecasting from a state-space model estimated up to 1990, showed that the market was over-priced during both the dot-com and the subprime mortgage bubbles. Implicitly, the feather forecast points to a sustainable level for the market but doesn't really display the level explicitly. To do that we need to remove the cyclical components and the month-to-month shocks from the model and run a counterfactual simulation for the stock market. The simulation is displayed above. Rather than reaching almost 1600 in the peak of the dot-com bubble, the simulation suggests that the market should have been at about 600. And, 1000 would have been a better level when subprime mortgage crisis broke.
Sunday, January 3, 2010
Need To Know vs. Need To Share
Discoverability is the first step in an effective system for information sharing, offering users the ability to “discover” data that exists elsewhere. Data is tagged at the point of collection with standardized information (e.g., who, what, where, when) and submitted to a central index. Just as a card catalogue in a library serves as a central index, directing users to relevant books—but doesn’t provide the book itself—these “data indices” point users to data holders and documents, depending on the search criteria used.
Saturday, January 2, 2010
The Dot-com and Subprime Mortgage Bubbles: An Example of State-Space Forecasting Techniques
First, as a point of comparison, I estimated a state-space model for the entire period. The model uses the state of the US economy as an input variable and the volumes and price data for the S&P 500 as the output variables. The fit of the model for S&P 500 volumes and prices in the figure above (dotted red line) is excellent.
Using a model estimated only up to 1990, the price fit is still good but the volume forecast (upper panel above) starts to deteriorate after 2005. Notice for both series that the model tends to miss the turning points--a common feature of all forecasting models (the models don't know that the bubble has burst until after it has happened).
Although models appear unable to capture turning points, they are able to identify developing bubbles using feather forecasting. A feather forecast uses the model to predict a number of periods into the future (thirty-six in the figure above for monthly S&P 500 data), starting from each period in the sample. Up to 1995, the model forecasts basic linear growth for S&P 500 prices. In 1995, however, the feather forecast identifies the developing dot-com bubble as having started in 1995 rather than the conventional dating of 1998. From 1995 to well into 2001, the feather forecast is predicting a collapse in prices. Indeed, from 1995 to 2007 (the last point where a 36 month feather forecast can be made) the feather forecast is warning of a collapse in prices. A conservative investing strategy would have been not to ignore the developing bubble but realize that one would have to be vigilant and liquid with any new investments made after 1995.
This then brings us back to a future forecast made with the model estimated up to 1990. The model is essentially predicting a sell off for 2010 (increasing volumes and decreasing prices). It will be interesting to see what actually happens over the next year. The model cannot predict monthly rallies and sell-offs or the turning points for recovery, but studying the feather forecast suggests that the S&P 500 cannot realistically reach 1000 for a few more years into the future. In any event, the usual disclaimers apply to this prediction.Forecasting Disclaimer
Friday, January 1, 2010
A Pessimistic S&P 500 Forecast for 2010-2012
The figure above displays a feather forecast of volume (the upper panel) and price for the S&P 500 (data from Yahoo! Finance). Although the models track the stock market data very well (displayed here), the feather forecasts (in this case, the feather forecast starts from every month in the sample and predicts forward three years) show that the S&P 500 was over-valued during the dot-com bubble, undervalued during 9-11 and over-valued again during the subprime mortgage crisis. In other words, using the models would have suggested a conservative investing strategy and warned of developing stock market bubbles.
The S&P 500 model is driven by the state of the US economy. Using financial terminology, the market fundamentals are determined by the state of the economy. Using systems terminology, the stock market is a hierarchical subsystem within the US economy. The three forecasts (dotted red, blue and green lines) in the graphic above suggest that the future will depend on the state of the US economy. Volumes will be flat while prices will either rally or remain flat based on the future of the US economy. Not really that surprising a range of forecasts.
When I use an actual forecast for the state of the US economy through 2012 as input for the model, the forecast is pessimistic: declining prices and increasing volumes, in other words, a sell off. You can compare my forecast to the one provided by the Financial Forecast Center here. Their forecast for prices also points downward (out to Jul 2010).