What I learned today:

• Shopping while hungry is not cost-effective, but it does result in some interesting impulse purchases. Chunky chocolate peanut butter has entered the house.
• Mean-variance optimization: Look at a portfolio of investments as a whole. Quantify risk and return, and their tradeoffs. Pick the portfolio that minimizes risk (variance) while meeting your return goal (mean). Markowitz, 1952.
• Easier said than done, as constraints (transaction costs, effect of the trades themselves, taxes) change optimal solutions, and error in estimation of parameters is significant and often magnified by the solution process.

What I learned yesterday:

• Rhododendrons are very cool.
• 12 hours out of the house on a Saturday is too much activity for me.