# Approaching Challenges with a Model

Techie people on the Internet have opinions on how YOU should live your life! “Here, take my advice; I wasn’t using it.” Well I will take you up on that, stranger:

(1) Focus on High-leverage Activities — “Leverage should be the central, guiding metric that helps you determine where to focus your time.” (related: Eisenhower decision matrix — “what is important is seldom urgent, and what is urgent is seldom important.”, “The best time to plant a tree was 20 years ago. The second best time is now.”

Gabriel Weinberg’s blog has more mental models-.

Expected value – a simple model for evaluating uncertain events (multiply the probability of the event by its value).

Corollary:Sometimes you’ll have to estimate probabilities when it feels really hard to do.

Example:Chance of winning NY lotto is 1 in 292,201,338 per game. Let’s say the grand prize is $150M and ticket price is $1. Then the expected value is roughly $0.5. Since $0.5 < $1, the model tells us the game isn’t worth playing.

Warning:Looking at expected value often isn’t enough. You need to consider utility to make good decisions.

See also:Techniques for probability estimates, shut up and multiply, scope insensitivity.

More mental models from Slava Akhmechet.