Choosing queues to minimize wait time

An article in the New York Times (September 7,2016) titled “How to pick the Fastest Line at the Supermarket” describes how choosing a line with one person with 100 items may be faster than a line with four people with 20 items each, with the former taking six minutes and the later taking seven minutes on average. The main issue, the article claims, is the setup time per customer – the time to say hello, pay for the purchase and say goodbye.  Given the estimated 37 billion hours spent by US customers in line each year, these details can improve service time.  But the article also claims that estimation of waiting time is a mental calculation with customers overestimating their wait times by 36%. How should service times design their architecture to influence both the actual time and perceived time ? How can service systems decrease setup time for queues, thus increasing productivity, while maintaining customer service perceptions ?

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9 Responses to Choosing queues to minimize wait time

  1. Kyle Harshbarger says:

    This is the second blog I’ve seen write about this article. The author also mistakenly thinks a customer has the choice between a “serpentine” line and single server queues (this choice is normally made by the business owner)

    I’m not sure the author found a ton of new info since Apu told us how to find the shortest wait time on The Simpsons 20 years ago…

    “Apu and Marge wait at the back of the long line in the express lane.

    Apu: Mrs. Simpson, the express line is the fastest line not always.
    That old man up front, he is starved for attention. He will talk
    the cashier’s head off.
    Abe: {Ah, there’s an interesting story behind this nickel. In 1957, I
    remember it was, I got up in the morning and made myself a piece of
    toast. I set the toaster to three — medium brown.}
    — Then he tied an onion to his belt, “Homer and Apu”

    Apu: Let’s go to…that line.
    Marge: But that’s the longest.
    Apu: Yes, but look: all pathetic single men. Only cash, no chitchat.”

  2. Sarah Rosnick says:

    This is quite possibly my favorite blog so far in the IMM program. In my mind, the most obvious answer is the development of the self-checkout lines. They are absolutely slower than a normal cashier handling the transactions, but the immersive type experience puts the burden entirely on the customer. They don’t have to greet the machine, there’s no need to tell it to have a good day, or to provide some sort of physical gesture to suggest warmth and appreciation. It gives the customer the perfect impression of control and speed.
    If we’re forced to accept a human is going to run this, then we find ways to distract the customer that’s waiting in line. Rudimentary ways to achieve this previously were with candy and magazines at the line. Now, we see things like commercials playing at gas stations while a car is fueling up. It gives a customer a chance to be distracted, provides name brands with a chance to influence and occupy the consumer’s attention, and ultimately gives many a better experience at the pump where they’re not staring impatiently at the numbers to roll over.
    In many cases, we thought we’d see a faster transition time in lines from the days when people would write checks since they would be limited to cash and cards. Surprisingly cash payments and making change is quite time consuming. I might set up specialty times that were card-only lines and I’d mandate that the cashier only begin conversation with the customer once they’ve swiped the first time. Additionally, I frequently find myself waiting for cashiers to approve whatever form of payment I’d like to employ…staring at a message on the card reader which tells me I’m waiting on the cashier. Much like the gas pump, I don’t really need to tell the cashier if i’m paying debit or credit. I should just be able to tap a button and move entire experience along before they’re through ringing up my groceries.

    • Jordan McCroskey says:

      You don’t talk to a self checkout machine? I find myself swearing at them as they don’t scan or the machine tells me to put the item in the bag that I already put it in the bag.

  3. Freddy Horn says:

    Obviously, some simple distractions such as implementing tv screens would help to reduce the perceived waiting time. Elevators also often have mirrors for the same reason, even though I doubt that they will have the same effect in a supermarket. People would probably be more hesitant to look at themselves with other customers standing around. A way to reduce actual waiting time would be to give shoppers mobile payment systems or use payment apps. For instance, a few years ago, the Italian super market chain Esselunga tested a system where customers were given mobile scanners with integrated credit card payment systems. The shoppers who chose to use this system had to put their credit cards in the scanners, scan the products that they wanted to buy, and confirm the payment at the checkout, which was just a stand where they returned their scanners. I tried it out myself and really liked it. The main concern was that this system would make it easier for people to steal. I wonder if they kept it or developed it further. I have not seen it anywhere else since.

  4. Kim Coldiron says:

    I am in complete agreement with Sarah on the self-checkout lines. So obvious, however, we are already seeing many of these removed from retail in Chicago. The two major drivers bring consumer challenges resulting in longer wait times and theft as Freddy mentioned. I personally prefer this option, especially when I am just picking up a few items but it can be frustrating to wait on someone insisting on using the self-checkout who has no idea how to use technology and continues to call on the support cashier… I’ll stop there! :/
    I had an experience similar to Freddy here in Chicago and it worked brilliantly. They recently opened an Amazon Bookstore near my home. In this bookstore, you can scan items as you shop using the Amazon App and make your entire purchase without ever approaching the register. Items are also slightly discounted through the app encouraging you to use this transaction method. I felt the whole experience was positive. The staff was able to mill about throughout the store assisting customers with needs at the point of sale and providing high-quality customer service, while the consumer was able to scan and quickly identify the price of a product without waiting in a line or having to ask for someone’s help.
    I also experienced something similar on a much larger scale a few weeks ago in Shanghai. The entire city (and most of the country) has adopted mobile payment capabilities, to the point it is rare to see anyone use cash or credit cards unless they are visiting. I understand that there is a communist component to government controlling how they operate but from an efficiency standpoint, it works very well. From bike rental, meal purchases, shopping, taxi and everything in between, the consumer simply swipes their phone and the transaction is complete. No waiting and no paper receipts. This doesn’t resolve the chit-chat situation but the transaction itself is quick and easy. They have also implemented a system where there is no need to wait for staff at the restaurant. There is a QR code on the table that you scan, the waitress has already linked your order to your table so you can scan and go as soon as you are ready. The apps are nicely integrated to allow you to share the expense with your dining companions as well.
    I will admit that I am a sucker for impulse purchases at the checkout so this type of distraction and marketing definitely works for a consumer like me and if I am totally honest, there are certain stores that I actually enjoy the checkout process for that very reason!

  5. Julia Eldridge says:

    I am glad that there was an article written about the wait time for 1 person with 100 items potentially being faster than 4 people with 20 items, as I have felt this affect a number of times. I often opt for the lines with fewer customers rather than fewer items, as I have noticed anecdotally that they seem to move faster. Once potential reason is in the set up time between customers. Often lines designated for fewer items have little space to place groceries, so the time for the transaction includes walking up to the counter, placing the items for purchase on at the register than the transaction itself. For normal lines, in the United States, there is typically a long conveyer belt to place items on. That means that as the person in front of you is wrapping up their transaction, you are able to ready all of your groceries so that they may be quickly scanned.

    When considering queueing patterns, I often think of Refael Hassin’s theory as described on the Freakonomics episode “What are you waiting for?” ( in which Hassin theorizes an optimal queueing pattern of having the newest customer go to the front of the line rather than the back. Though an interesting theory, there are many issues with the theory, primarily that it could not be used for goods that are needed such as groceries, as the person fourth in the line may never be served. While I do not believe this practice could work in the real world as it is today, I often find myself pondering its merits as I wait in lines and contemplate if it would be affective in the current situation.

  6. Michael Minor says:

    I enjoyed reading that article because I hate lines at the grocery store. I often use the self-checkout line for couple of reasons, one there is rarely a line and two I don’t have to wait for the person in front of me to finish writing a check. Yes, people in Indiana love to write checks at least when I’m in line. Customers perception of time is mainly based on their engagement. Self-checkout keeps the customer engaged throughout the process causing them to forget about time. You’re happy even if you spent four minutes trying to find the SKU for broccoli, just because you’ve avoided the other lines. In a conventional line, there is little to distract you other than some magazines you wouldn’t read or candy and chips selection you want to stay away from. I like Freddy’s idea of television; I suggest a small monitor that plays local news captions to keep people entertained.

    Costco is the only place that I can get behind a person with two carts and not blink an eye. They have a system where people are always moving and the customer engaged. There is a person taking your groceries out the cart at the same time the customer has there wallet out to show membership and getting to their method of payment ready, with another person bagging and carting. It’s a very smooth process that others could easily follow.

  7. Jordan McCroskey says:

    I’ve enjoyed the grocery store examples and the comments of the other class participants. I’m apparently in the minority as I loath self-checkout. Mainly because the software UI is bad and the scanning speed is slow. As this tech gets better I’ll be more willing to give it a chance.
    I am constantly amazed at the difference day to day when I go to Starbucks. Some days the line moves quickly and some much slower. I’m learning that the ability to preorder and have your drink ready and already paid for is key to a quick process. When I preorder I typically don’t wait – and my drink appears fresh and still hot. I think as more stores encourage a process that allows consumers to skip the line and prepay, the setup time will decrease (especially the time waiting for the person in front of me to pick all the options on their drink (it’s just coffee people and you’ve been standing in line – you should have your drink order ready to go by the time you get to the register).

  8. bairdjb says:

    Ok, I first have to say I had a great chuck at your terminology not that we all know you Sarah’s (i.e. “no need to tell it to have a good day, or to provide some sort of physical gesture to suggest warmth and appreciation” and “If we’re forced to accept a human”). Kim, I really enjoyed your venting at the beginning of your post.
    However, in all seriousness, I think that Kim and Sarah hit the proverbial nail on the head. I agree that in general a self-service line at the grocery store is perceived to be quicker when in fact it might not be the case. Although I see it as a competition/race and thus it is faster than checking out in a checkout line. Customers concept of time is skewed due to their high level of involvement and the reduced need for interaction outside of what is needed to complete the process. Conversely, I see self-service lines at McDonald’s and Panera drastically increasing the order placement times. This is do to the fact that unlike grocery stores the customer is required to search for the item to order in a process that is unfamiliar to the customer.
    Thinking specifically about retail stores. I think more stores need to adopt a process of identifying what a person is purchasing before they get to the checkout. There is no reason for the technology we have today that people need to load their carts, unload them again to be scanned and then placed back in the cart. This entire process needs to be streamlined. Which I guess honestly means we are coming to a point in time when there really is no need to go to the store. As the more efficient is simply ordering online either for home delivery or curbside pickup.

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