Better Decisions at the Supermarket
(I just went to a supermarket and wanted to share some thoughts. The decision theory stuff will be elementary. Here is a LW FAQ on decision theory if you actually want to learn the basics.)
Today I had a class on repeated games, and went shopping by myself.
Usually when I grocery shop with someone, there is a high probability we will end up having an argument.
Behind the debate on what kind of yogurt to buy, there is a real issue: misaligned values.
I believe understanding what we each value can help to better communicate on what matters. More importantly, it might bring better decisions.
I used to spend hours in supermarkets, thinking about how to optimize my cart because I did not have an accurate model of my own utility function.
Today, I ended up listing the factors which mattered the most to me:
Money: I do not have an infinite budget for food. I am concerned about overspending on foods what will become stomach mush.
Time: Time shopping and time spent cooking.
Health: Food quality might impact my digestion, short-term mood but also long-term health. High quality food might prevent diseases and improve my longevity.
Biological Needs: Our body evolutionarily needs a certain quantity of protein, lipid, etc. Therefore, if I already have carbohydrates at home, “buying protein” is more important than “buying carbohydrates”.
Quantity: I want to buy the maximum amount of food I can so that I don’t need to come back, yet I can’t carry too much weight
Some useful ideas about the above criteria:
The law of diminishing returns explains how, all things being equal, optimizing one parameter will less and less impact the utility function.
The time criterion is highly correlated with every other criterion. Indeed, if I try to optimize my protein intake, I will spend some time thinking about it.
People tend to value low-risk instant utility, rather than some reward which may arrive later. It is possible to introduce a discount to take into account that I prefer $99 now than $100 tomorrow (depends on the inflation rate, etc.)
Take time into account in your decisions. A simple heuristic can go a long way:“if I save less than a dollar, I should spend less than 3 minutes on optimisation (Assuming a wage of $20/hr for the value of your time)”.
Second, you might want to consider the whole process as a coalition formation inside your cart.
Third, write out your factors. You know what matters to you. Knowing how it matters is called instrumental rationality.
This is the 10th post of a series of daily LessWrong posts I started on April 28th.
Next post: Applied Coalition Formation
Previous post: Beliefs: A Structural Change
EDIT: incorporated Elo’s suggestions and changed underline to bold