In a 1970's speech following Benjamin Graham, Robert G. Kirby made the following argument:
Economic analysis can be used to make investment decisions. In doing so, I would be inclined to concentrate my attention on two areas. The first would be in the determination of future, long-term interest rates. We have moved into an era where there are no longer two watertight compartments of "stock money " and "bond money." Equities and fixed income securities now compete for the same investment dollar. A critical factor in making good investment decisions is what the basic wage of capital is going to be in the future.
Today, there is a knowledgeable camp of people (Hoisington, Zell, Watsa) who believe that long term treasury rates will continue downwards. In such an environment, it is the high quality company, one with strong competitive advantages, that will prosper as an investment. This is because in the long run, the market value of companies will track their growth in earnings. In an environment where long term treasuries yield 3%, it is the marginal company that will feel the most pressure on its Return on Investment (ROI), and hence earnings. Meanwhile, the high quality company will be better able to maintain its ROI due to the moat surrounding its business. So, finding a company that can maintain 10% long run earnings growth becomes much more valuable in a 3% discount rate environment than in a 7% setting. Such companies are difficult to find at a meaningful discount, but you can bet I'll be watching closely for anything if further market turmoil continues.
It is also interesting to note the second economic factor Kirby mentioned to watch out for: whether the future will be one of saving or spending. With the consumer "tapped" out and heavily indebted, it would seem that our future is one of savings. Such a shift could have a major impact on earnings; but again, it is the high quality company that will least likely feel these effects.