My cousin (econ major) and I (stats major) kicked around an idea for dynamic grocery pricing based on line length. We never got any data ("kicked around" the idea, remember), so we didn't even get to the point of realizing the y-intercept wouldn't be zero.
Something will happen there, though. Lines = deadweight loss, and deadweight loss = room for improvement.
> Lines = deadweight loss, and deadweight loss = room for improvement.
Do you mean deadweight loss for the grocery store, or for the customer? Relatedly, does the grocery store care about deadweight loss for the customer?
If every grocery store in town has the same expected line length, then the entire cost of line length is borne by the consumer---since the line lengths are in equilibrium, none of the stores feel economic pressure to reduce their line length, and the line length is a fixed cost of food shopping (unless latency becomes comparable with the length of time a store is open during the day, in which case it's actually limiting the number of customers they can process per day, but I find this highly unlikely).
Granted, a store might try to differentiate itself by reducing its average line length, but there are many other (perhaps more important) factors that go into a consumer's choice regarding grocery stores, e.g., Wal-Mart mega-food-store competes on prices, Whole Foods competes on its customers' self-satisfaction (I kid, I love Whole Foods).
Intuitively, it feels like grocery store line length is in the noise when considering the decision process for most consumers, especially since I can get zero line length at almost any store by going during off-hours. If it's in the noise, there's no selection pressure to improve it.
I meant for the customer, and while I agree that grocery stores don't care about deadweight loss for their customers, I think they could.
I think the chief reason line length is considered noise rather than signal is because it's so unpredictable. When it's known, people do a great deal to minimize their time spent in line. They go to the store at off hours; they switch lines once they're standing in them. I know my local Taco Bell gets a lot more business from me because of their speedy response time, vs. the teriyaki place next door that I like more, but takes forever. And my college's bookstore has had a great deal of success with putting live camera feeds of their lines (or lack thereof) on their website.
But with grocery stores, I couldn't really tell you which of the two grocery stores in my area would have a longer line. They're about the same, and that's close enough.
So you'd need a pretty big delta for line length to become a differentiating factor between stores. The current system of a cashier scanning items individually probably won't see drastic efficiency improvements without drastic changes, so...drastic changes are needed.
After a certain point, changes in "line length" become "presence or absence of a line at all." As jonnathanson says below, electronic scan-as-you-buy is probably the future there(Smith's, in answer to my cousin's email inquiry, mentioned they were testing a portable bar code scanner). I'm under the impression that grocery stores have pretty cruddy margins, so maybe I shouldn't read that much into "in testing." If anyone out there is dying for a startup idea, I think this one is worth a look. (Before you say it, I'm working on another project, and my cousin left for grad school.)
Since few things are more self-satisfying than sailing out of a store without waiting in line, maybe Whole Foods will be the first? ;)
Something will happen there, though. Lines = deadweight loss, and deadweight loss = room for improvement.