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DVD Smith
1290436.  Tue Jul 17, 2018 10:53 am Reply with quote

One long winding queue is faster then multiple short ones.

For a shop with multiple cashpoints side by side, waiting times are much shorter when the shop uses a single winding line (called a serpentine line) rather than a different queue for each till. This is because if one person takes ages when paying for something then the people behind can just move past them to the next available cashpoint.

This is another finding from Dr Richard Larson, as reported here.

 
nathanvanwyk
1295746.  Wed Sep 19, 2018 4:15 am Reply with quote

Men are more likely to give up on a queue than women. Men start to inflate the amount of time they believe they have waited after two minutes. Women give it three minutes.
The term “faffing” refers to the time delay when a person gathers their things after paying at checkout. The average faffing time is 3.17 seconds.
Once a wait lasts longer than three minutes, the perceived wait time multiplies with each passing minute. After five minutes pass, perceived wait time is doubled.
A shopper or manager can calculate the expected wait time in any queue using Little’s Law, the formula created by John D.C. Little. The formula is: Average Wait Time = Average Number of People in Line ÷ Arrival Rate. For example, if there are 8 people already in line with about 2 customers entering the line per minute, the average wait time would be about 4 minutes.
People overestimate their wait time by 23% when they are not told how long their wait will be. For example, if the actual wait time is 13 minutes, people assume it will take around 16 minutes. That’s why we suggest using a sign to tell your customers approximately how long they can expect to wait.
The term “reneging” refers to a customer leaving a queue that they believe they have spent too much time in.
A single-file line leading to three cashiers is about three times faster than one line for each cashier. This is called unified, or single-line queueing, and it’s something we really believe in. Click here for more information on the proven effectiveness of unified queues.
The “balking index” is a scientific formula that calculates the number of people who will abandon the queue (or renege) in a given time. This helps managers determine the number of staff needed to properly service their customers.

Reference: http://blog.linelogic.com/blog/2013/05/29/10-little-known-queueing-facts/

 
DVD Smith
1295751.  Wed Sep 19, 2018 4:54 am Reply with quote

A 2015 study by two professors at the University of Southern Denmark found that the most optimum way to serve a queue is actually "last come, first served", i.e. to serve the back of the queue before the front.

This sounds counter-intuitive, but according to the professors, if people know in advance that the people at the back of the queue get served first, then they don't rush to be there as early as possible but instead arrive at more staggered times. This means the whole operation runs more smoothly, resulting in an overall better experience for everyone.

However, if people don't know in advance that the last-come-first-served rule is in force, you end up with a lot of angry customers who have been waiting a long time.

https://www.bbc.co.uk/news/magazine-34153628

 
suze
1295782.  Wed Sep 19, 2018 11:23 am Reply with quote

nathanvanwyk wrote:
A single-file line leading to three cashiers is about three times faster than one line for each cashier. This is called unified, or single-line queueing, and it’s something we really believe in.


I've heard this once or twice before, and I dare say that the good husband would be able to give me the mathematical proof that it is so. (I shall thus not ask him, for fear that he will do so.)

But if it is so, why are supermarkets not usually organized this way? Banks and post offices by now mostly are, and so are the retail outlets of Mr Marks and Mr Spencer. Supermarkets rarely are though. Is this because the people who run them dispute the math, or because they are just being awkward?

 
DVD Smith
1295825.  Thu Sep 20, 2018 4:18 am Reply with quote

suze wrote:
But if it is so, why are supermarkets not usually organized this way? Banks and post offices by now mostly are, and so are the retail outlets of Mr Marks and Mr Spencer. Supermarkets rarely are though. Is this because the people who run them dispute the math, or because they are just being awkward?


Because customers in banks and post offices generally don't have huge trolleys full of a week's worth of groceries in them. Navigating those around a huge snaking single-file queue would probably be more of a hindrance and a hold-up than the time saved by having one queue per cashier.

There's also the question of space - cashiers' desks at supermarkets are much longer than in other shops (with conveyor belt + bagging area) so having individual queues alongside each conveyor belt is presumably a more optimal fit for the limited floorspace available.

 

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