Chalk one up for Economics...

There's a concept in economics known as "Expected Value." Last night, it paid off for me.

Got a call from a market research firm. They wanted 20 minutes of my time to answer questions about my new computer purchase. In return, they offered me a 1 in 10 chance of a $50 gift certificate.

That make the "expected value" of my 20 minute $5. In other words, my time is worth $15/hour. Now, you could say, what would I do with the time otherwise? However, I quickly made the calculation and determined that I could potentially earn more than $5 by reviewing some stocks in my portfolio and taking an online course, which I did.

I told the guy that my time was worth more than that, said thanks, and hung up.