Comparative advantage: better at everything, still not doing everything

Meera in Pune cooks better than her husband Arjun. She also keeps the household accounts better than he does. So after her office day she makes dinner, then sits down with the hisaab notebook, while Arjun watches the cricket highlights and feels a little guilty. Nobody is lazy here. Both are tired in different ways, and the evening still feels unfair.

What the model says

Comparative advantage asks a different question from "who is better at this?" It asks "what does it cost you to do this, in the other things you could have done with the same hour?" The idea comes from the economist David Ricardo, who used it to explain why two countries can both gain from trading, even when one of them makes everything better.

The useful word is cost. Being better at a job is not the same as being the right person for it, because your hour is only spent once.

Meera and Arjun, with numbers

These are the couple's own numbers, kept simple. Dinners for the week take Meera 6 hours and Arjun 8 hours. The weekly accounts take Meera 1 hour and Arjun 4 hours.

Meera is faster at both. But look at how much faster:

• On dinners, her hour does the work of 1.3 of his hours.
• On accounts, her hour does the work of 4 of his hours.

So her edge is small in the kitchen and very large in the notebook. If one job has to leave her hands, it should be the one where she saves the least, which is cooking. Arjun takes over most of the dinners. Meera keeps the accounts, which take her an hour and would take him four.

If you count only hours, Meera doing everything is still the quickest way to finish the work. That is the honest part. But her hours are not free. The hours she gets back each evening can go to rest, to her sister's call, or to the course she keeps postponing. Arjun, who was only waiting to be asked, now has a real job, and the load stops sitting on one person.

Where it stops

The model counts hours, and a home is not only hours. Meera may love cooking on Sundays, and that is a good reason to keep it. Arjun may need a few weeks before his dal is something the family looks forward to. Do not use this model to hand someone the jobs they dislike and call it logic.

It also says nothing about who is worth more. It is a way to look at a split, and the split is still a conversation between the two people.

One thing to try this week

Pick one job you do only because you are good at it, such as the monthly hisaab, the bank visits or the school forms. Write down roughly how long it takes you and how long it would take the other person. Then hand over the job where the gap is smallest, and tell them you will not redo it, even if it comes out a little different. Do this before Sunday and write down on Sunday how it went.

This is a way to think, not financial, medical or legal advice.

Each Sunday: one mental model and one real decision to try it on. The /models library keeps them all in one place.