Why the group always over-orders

You know the moment. The check lands, someone says let's just split it, and the number is bigger than the meal felt like. Nobody quite remembers ordering the second bottle of wine or the extra round of starters, and yet there they are on the bill.

This turns out to be one of the most studied problems in behavioral economics, and it has a name.

The experiment

In 2004, three economists ran a field experiment at a restaurant near the Technion in Israel and published it in The Economic Journal. They sat people down in groups of six and gave each table one of three deals. Some paid only for what they personally ordered. Some split the whole table evenly. Some ate for free, with the researchers picking up the tab.

The pay-your-own tables spent about 37 shekels a head. The split-evenly tables spent about 51. That's roughly a third more food and drink, ordered by the same kind of people, for no reason other than how the bill was going to be divided. The free tables spent the most of all, around 82.

Why it happens

The logic is uncomfortable once you see it. When you're splitting six ways, ordering one more appetizer costs you a sixth of the price, but you get the whole thing. So you order it. The catch is that everyone at the table is running that exact calculation at the same moment, so everyone orders the extra thing, and the check balloons for all of you.

Economists call this the unscrupulous diner's dilemma. Everyone behaves reasonably on their own and the group ends up worse off together. It was described in theory about a decade before anyone tested it in a real dining room.

The part that stuck with me

The researchers also asked people, before anyone ordered, which arrangement they'd prefer. Most of them, 19 out of 24, said they'd rather just pay for their own food. They didn't want the even split. They over-ordered under it anyway, because the alternative was being the one person who got a salad while everyone else feasted on your dime. Nobody wants to be the sucker, so the whole table spends up.

So should you always itemize?

You could read all this and decide the even split is a trap and you should always pay for exactly what you ordered. Not so fast, and the authors say as much themselves. Their diners were strangers. When you eat with the same friends every week, it evens out. You buy the drinks this time, they get them next time, and itemizing every coffee would be exhausting and a little joyless. Among people who actually trust each other, splitting evenly is the sensible shortcut, not a con.

The real problem is narrower. It's being stuck with one rule for every table you ever sit at.

Where dvup comes in

This is the whole reason dvup has more than one way to split. When it's your regular dinner crew, split the check evenly and move on, two taps. When it's a big table where one person had the tasting menu and another had a side salad and a water, scan the receipt and let everyone claim what they actually got. You decide per meal, instead of picking one rule at the start and living with it forever.

Split evenly when trust and repetition make it fair. Split by item when the orders are lopsided and the group is big or you'll never see half of them again. The app just makes both of them fast.

Questions