Why is 4 out of 5 stars good for a restaurant but near-catastrophic for an Uber driver? Why do hotels and movies have two kinds of ratings but books and consumer electronics only have one?
I mean, a rating is just a rating, right? If I like it, I give it more stars. If not, less.
Turns out, it’s not that simple.
If you’ve ever driven for Uber, or you know someone who has, then you know how hard they fight to get five stars from every rider. Why? Why do fractions of a star below perfection matter for rideshares but not for, say, food trucks or hair salons?
To start, you have to understand that consumers occupy a position of near-total uncertainty. We have no idea which coffee maker is best for us, or whether it’s worth it to drive across town for a higher-rated mechanic? (Couldn’t the guy around the block fix the AC just as well?)
In the old days, consumers knew the price of a good or service and that was about it. Clever marketers would spend a lot of time designing branding and packaging that signaled certain cues in an attempt to nudge people to purchase. Unless we happened to know someone who had personal experience with the product, there was little to go on but looks and price.
If a shopper was contemplating a large purchase, such as a car or computer, they might consult a trusted expert or magazines like Consumer Reports, which made a living testing home appliances and financial services the like — products people were willing to research before buying.
But here, as everywhere, the internet cut out the middle man. With the arrival of the internet, consumers could start sharing our experiences directly with each other. If we had a bad experience with a doctor or lawn service, we could post it on sites like Google, where others could do the same.
That meant that star ratings, ostensibly a simple measure of quality, aggregate numerous experiences, and so indirectly measure a great many variables besides quality — for example, consistency.
Human are biologically risk-averse. They like consistency, which is why McDonald’s is perennially popular. We want to know what we are getting and will often choose a mediocre service that is consistently mediocre over one that is typically extraordinary but occasionally bad.
In other words, above a certain level, quality starts to matter less than other considerations, and those considerations vary by product.
The reason Uber drivers need 100% 5-star ratings is because a ride from point A to point B is effectively fungible. The biggest determinants of quality — traffic, weather, speed limit — are out of the control of the driver.
That didn’t use to be the case. We starting tipping taxi drivers because in the days before Google maps, local knowledge of shortcuts and alternate routes, not to mention real-time knowledge of congestion (communicated by CB radio), varied by driver, and a good one really could get you where you were going faster.
That’s largely not the case anymore. So, though taxis have not been fully automated, an important first step has already happened. Urban transportation has been commodified, and there is nothing more ripe for automation than the repetitive production of a commodity.
What does that have to do with star ratings? As much as they are risk-averse, humans also dislike choosing at random. Where they don’t have a reason, they will invent one (and rationalize it after the fact.) However, they’re also lazy, and the reason they invent will be the easiest, most minimally defensible one possible.
The easiest way to pick between Driver A and Driver B is star rating, because it’s staring right at us in the app. We may know there is no real, measurable different between a driver with 98% 5-star ratings and one with 97% 5-star ratings, but what other determinant is as simple and obviously available?
But what is true of Uber rides is not true of books or restaurants, where two of the same type will still be very different. Books are not commodities, not because they’re art per se but because there’s no accounting for taste.
How do you compare the latest Tom Green tearjerker to the latest installment of a space opera series, where both have roughly identical star ratings? Does that really mean we’re going to enjoy them equally?
Of course not. We know not every book is trying to be Shakespeare. Some are trying to be nothing more than a fun summer read, and if that’s what we enjoy (or think we will enjoy), then we want a book that does a good job of that, not one short-listed for the Booker Prize.
This is why hotels have multiple ratings on travel sites. The first, determined by the site, establishes the overall quality of the hotel. Five-star hotels are supposed to be the epitome of luxury. 2-star motels are a cheap place to crash for the night.
The second rating, aggregate customers reviews, determines how well the property met that expectation. You can have a 4-star 5-star hotel, for example, where they didn’t bring you fresh towels every day, and a 5-star 3-star hotel, where they did.
Online movie rental apps are getting at something similar when they include both an aggregate critic rating as well as an audience rating. The critic rating hints at what kind of movie it’s trying to be (no one listens to critics) and the audience rating lets you know how well it achieved that.
In my world, NUMBER of reviews matters more than star rating, which is why I’m constantly urging people not to feel bad about being honest. Above a certain level, it really doesn’t matter how many stars you give it. Really.
What’s matters is that you add your rating to the total number, because readers use total number of ratings as a proxy for popularity. A book with more reviews is assumed to have engaged more people, so readers consistently tend to pick, say, a 3.6-star book with 800 reviews over a 4.4-star book with 80.
(Partly, that’s because readers don’t know whether, in giving a book four stars, you are saying it was a 4-star book or that it did a 4-star job of being whatever kind of book it was trying to be. In conversation, people will even switch between the two without realizing it.)
This situation is unfortunate, in a sense. As a class, readers tend to pride themselves on their independence of thought, yet, when choosing a book, market research suggests they consistently follow the crowd, which is why publishers spend so much time and effort manipulating the NY Times bestseller lists.