Why You End Up in the Slowest Supermarket Line

by in News, July 21st, 2014

Why You End up in the Slowest Supermarket LineIs it you, or does it feel like, no matter how hard you try to pick the shortest, fastest-moving line at the grocery store, most of the time you make the complete wrong call and end up crawling along at a snail’s pace, stuck behind someone who needs a last-minute price check on an item or is fumbling around for his or her frequent-shopper card or is simply bent on chit-chatting the afternoon away with the cashier — while customers who come after you and slide blithely into other lines are out of there in record speed?

It’s not just you.

“When you’re selecting among several lines at the grocery store, the odds are not in your favor. Chances are, the other line really is faster,” science writer Adam Mann explains in Wired. “Mathematicians who study the behavior of lines are called queueing theorists, and they’ve got the numbers to prove this.”

There’s an equal chance of a random, unpredictable delay occurring on any of the lines, Mann notes, and if there are, say, three lines to choose from, you have only a one-in-three chance of being in the fastest-moving one — and a two-in-three chance of standing miserably by while the customers in another line move faster than you.

Ushering all customers into a single “serpentine” line — a la Trader Joe’s, airline counters, fast-food restaurants and banks — with the person at the front of the line proceeding to a register as it becomes available, offers a solution. In a three-register situation, Mann says, it’s “about three times faster on average than the more traditional approach.” Plus, if there’s a delay in a transaction at one cashier, everyone waiting behind them for a cashier suffers equally — but not terribly, since other cashiers can keep the flow moving.

“The serpentine line … offers important solace,” Seth Stevenson wrote in Slate in 2012. “You absolutely never have to see someone arrive after you and get served before you.”

So why, if they are more efficient and equitable, don’t all grocery stores use serpentine lines? Customers don’t like them, in part because they look longer, and also because, while it removes the possibility of losing out by picking the slowest line, it also prevents them from winning by picking the fastest one.

“We human beings like to think that we’re in control of our lives and can beat the system if given the chance,” Mann notes. Even if the math and the lady digging in her purse for exact change for half an hour are clearly working against us.

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Comments (14)

  1. MoHub says:

    I'm a huge believer in serpentine lines, but I think an additional problem is that they require more real estate at the front of the store to keep all the customers in a single, albeit zig-zagging line.

  2. FoodieFancier says:

    Why do I end up in the slowest line? Because I've chosen to go to the checker who doesn't rub their head, sneeze, wipe their nose on their sleeve and treats the customer's items with respect. That's why that line is so long.

  3. Ruth Ann says:

    It seems though that even when I change lines to a line that has been going faster; it suddenly slows down. Explain that one with math.

  4. FancyFeast says:

    MoHub – I was thinking that exact same thought! I also like the self-checkout so I don't have to deal with a cashier who has a cold and wiping his nose just before touching all my merchandise! (Happened to me at Target) I also like bagging my own groceries. I don't need 6 bags for 7 items. And if my bread gets squashed it's my own fault!

  5. Happy Cashier says:

    As a cashier I can tell you that many customers do it to themselves. They refuse to stop at a register that has no line because they don't think it's open…even when the light is one and a cashier is standing there. They might ask "Are you open?" which makes me wonder because why would I BE there otherwise? We do…but not often enough…have a floor manager who will direct shoppers to an empty/slower register. There's also the fact that customers just won't walk a bit further on and find a less lengthy line. Why? Because they parked at the "wrong end" of the building to do that. I cannot believe how lazy people are sometimes.

  6. Kel says:

    I love the self-checkout lines, but even they slow you down because if you have alcoholic beverages, the insist on sending over a cashier to check your I.D. What a waste of time! Every state I.D. has a magnetic strip in it; why can't I just swipe my I.D. and keep speeding right along?

    My only solution is to shop on Tuesday or Wednesday, and to avoid the first 20 days of the month, as all the welfare recipients receive their handouts from the 1st through the 10th. By the 20th, they're usually out of money and out of the way.

    • Tom says:

      Well–simple on the alcohol. If I'm under 21, and the cashier isn't paying that much attention, which is not uncommon, I just swipe my friend's ID and keep moving, and Tom Thumb or whatever store will have just sold alcohol to a minor.

      • YJB says:

        Your friend would feel free with you always having his/her drivers license? If your friend were with you, why wouldn't he just show the ID? Sure, technically it can be done, but how often in reality.

    • yjb says:

      What's different on Tuesday and Wednesday?

  7. Sky says:

    If you're standing in a super long line and there's suddenly a shorter line next to you, everyone, including the people in your line, will head to that shorter line, making that line the longer one, and yours the shorter one. I rest my case.

  8. kenneth g thomas says:

    im going to JFK and MONTREAL, QU via Train. I will eat at The Smoke Joint and Katz. Wish luck . -Kenny !

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