When Bill Eckhardt left the University of Chicago and foresook his nearly completed PhD in mathematical logic in 1973, he did not abandon his educational pursuits; rather, he focused them on a myriad of disciplines that supported his research in creating trading systems. Eckhardt joined high school friend Richard Dennis as a trader on the Mid-America Exchange. The two would later become partners in C&D Commodities, where they created technical trading systems and launched the famous turtle trading experiment. Details of the turtle experiment have become legendary, but the proof of its value can be seen in the many highly successful trading businesses it launched, as is demonstrated by our class of Top Traders of 2010. Eckhardt launched his own commodity trading advisor (CTA) in 1991, which has produced a compound annual return of 17.35% over 20 years and earned 21.09% in 2010. In addition to building trading systems, Eckhardt has developed a science of trading and written academic papers on the philosophy of science. Here, we discuss his scientific approach to trading.

Futures Magazine: Many in the traditional investment world cling to the notion that markets are efficient. Trend-following is not valid under the efficient market hypothesis (EMH) but here you are 30 years later. Why has the EMH persisted? Talk about this anomaly.

Bill Eckhardt: The random walk model of price change has been so durable because it’s nearly correct. The difference between futures prices and certain random walks is too small to detect using traditional time series analysis. Incredibly, this difference is detectable using trading systems.

FM: How do trading systems do this?

BE: Trading systems can be highly sensitive to non-linear relations in price series. So why doesn’t this revolutionize the modeling of price series? Statistical estimators probe particular features of the price series; they are equipped with confidence levels, give information about possible models, and are useful for prediction. From the point of view of the modeler, trading systems do not locate specific features of the price series; they have no confidence levels and are useless for prediction. Worst of all, they say little about any possible model. Trading systems can be highly remunerative, but they don’t tell the modeler what he or she needs to know. In the same way models, although valuable in other respects, do not help in designing trading systems.

FM: You have spent a lifetime in trading and in research. Name a couple of simple truths that you have discovered.

BE: Improve your trading or it will degrade; there’s no coasting in this game. You can be creative in research but don’t trade creatively; in other words, stick to your systems. Trading is a little like morality in that it’s a lot easier to know what you should do than to do it. Finally, use only robust estimators and very large samples, not dozens, but thousands.