Why do Investors Care?
Investors need to monitor the economy closely because it usually dictates how various types of investments will perform. The stock market likes to see healthy economic growth because that translates to higher corporate profits. The bond market prefers less robust growth and is extremely sensitive to whether the economy is growing too quickly, which could set the stage for inflation.

The APICS survey gives a detailed look at the manufacturing sector. The diffusion index does not move in tandem with the NAPM index every month, but sometimes the two do move in the same direction. Since manufacturing is a major sector of the economy, investors can get a feel for the general economic backdrop for various investments.