There's a mathematical formula for picking the fastest line

CTV News Channel: Which line is most beneficial? Nicos Georgiou, math and statistics lecturer, explains whether there is a way to choose the fastest line.

Unless maybe you’re British, lining up for anything is boring and best avoided.

But it’s not always possible to cut the line.

So what do you do when you’re at the grocery store and you need to pick the quickest checkout line?

Intuition likely tells you to choose the shorter line. After all, a short line generally means a more efficient server and fewer people to wait behind.

But according to University of Sussex mathematics lecturer Nicos Georgiou, picking the short line is often the wrong choice.

“It’s always unclear which one will be the fastest queue because there are so many random events that can happen that can delay the one that you’re in,” Georgiou told CTV News Channel, citing examples of someone who chooses to pay using only coins or a person using a bunch of coupons.

According to Georgiou, the only way for there to be an efficient line is if there’s just one queue, like the ones at customs in airports.

“It’s the most beneficial because it’s fair in the sense that the customers are in a first-come, first-serve basis,” he said.

But for non-serpentine lines, Georgiou and his colleague came up with a mathematical formula to pick which will move the quickest.

The formula takes into account two variables: service time distribution and arrival time. Service time distribution measures how long it will take for a customer to be served, while arrival time is how often someone joins the line.

Depending on what those variables are, the longer line might actually be the fastest.

But here’s some bad news: the math formula can only be done by the store owner, not the customer.

“There’s a lot of data that decides which queue is efficient or not,” said Georgiou, implying that customers don’t have access to enough data to logically make the right decision.

So if you’re the customer, Georgiou advises to pick a line at random, although there are some psychological factors that can help.

“Right-handed people tend to go to the right, so your best option is to go to the left because it will be less crowded,” he said.

But whatever you do, don’t try and look at other lines.

Georgiou explained in his article that comparing to other lines makes you vulnerable to the inspection paradox, where you think the line is moving slower than it actually is.