Cramer's Get Rich Carefully: X ray vision

I recently read Jim Cramer's "Get Rich Carefully." One of the chapters that I found most interesting dealt with the concept of the key earnings reports  Because certain stocks and industries  show what's happening on a larger scale. The following are the companies conference calls that he follows to gauge the strength of various sectors:

• Caterpillar 

 Sells construction equipment world wide, which reveals the strength of markets especially in China where government numbers cannot be trusted.

• Alcoa 

The Aluminum giant.  A leading predictor of the economic cycle

• Home Depot

 Which regions are the doing the best. You can gauge the demand from a variety of home products

• Union Pacific

Rail road lists which market it is selling and where is demand.  Take Q2, 2014 earnings CC:

 "Frac sand shipments are up 25% and more growth is seen."

Sure enough, EMES, HCLP, and SLCA all beat and guided upwards.

Cramer also mentioned  Slb, Jpm, and Fdx as Conferences calls to pay attention to.