Ten Principles of Economics How People make Decisions 1. People face tradeoffs 2. The cost of something is what you give up to get it 3. Rational people think at the margin 4. People respond to incentivesHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc. Ten Principles of Economics How People Make Decisions 1. People face tradeoffs. 2. The cost of something is what you give up to get it. 3. Rational people think at the margin. 4. People respond to incentives