Elimination by Aspects: Goal-Oriented Decision Making

In 1972, psychologist Amos Tversky described a way that we naturally make decisions. He called it “elimination by aspects”. It’s a method that uses a goal-directed strategy along with some simple rules, to quickly reduce options, resulting in a decision that is satisficing or quote, “good enough”.

How it works, is we start with a goal in mind like buying a phone, getting some lunch, or choosing a book to read. Dependent on the goal, you start with a single aspect. Often times it’s an aspect that’s crucial, it’s a “must have” or a “deal breaker”. For example, maybe you have a maximum price that you’re willing to pay for a phone, or you only have a certain amount of time grab lunch. For a book, maybe it must be a certain genre, or maybe it needs to be an audiobook, because you plan to listen to it while you exercise.

For example, let’s say our goal is to buy a camera. We start with a total of all the cameras available. But, then we decide that one of our most important aspects is to spend no more than $500, eliminating all the cameras above this price. This is known as “goal-directed pruning”. Next we want to be able to upload our photos instantly to the cloud, so we decide to eliminate all the cameras without wifi. And because of the type of pictures we plan to take, we also want a good optical zoom, further reducing our options. Last, we decide to eliminate any cameras that don’t have solid reviews, leaving us with 3 options to contrast and compare.

As a side note, when Amos Tversky first published his article on elimination by aspects, online shopping didn’t yet exist. It would be another 20 plus years before companies like Amazon, Walmart, and Alibaba designed their websites to leverage the power of elimination by aspects. Nowadays, instead of aspects, we commonly use the term filters in order to help us narrow down our options.

Benefits
The main benefits of elimination by aspects is that it is fast, low effort, and generally effective. It most often leads to a “good enough” decision. It’s a method that matches the way most of us naturally make decisions, helping us to navigate our preferences and simplify even the most complicated of choices.

Limitations
However, t’s useful to note, that elimination by aspects is not a strictly rational approach. You are not going through the process of identifying all the options, weighting the various pros and cons, and conducting a thorough cost-benefit analysis. This means, based on the order that you apply the filters, there is a greater risk that you overlook a “best” option. If you change the order of elimination, you probably will end up with a different final choice. And elimination by aspects doesn’t allow you to balance trade offs.

In Practice
In practice, it’s best to keep in mind that elimination by aspects is really a tool to help you save time and make a “good enough” decision, not necessarily the optimal decision. This is probably fine for decisions where there are a ton of options and the consequences of making a bad decision are relatively low. On the other hand, for high stakes decisions, it’s probably a good idea to slow down, and go through the filtering process multiple times, switching the order of the various aspects, as to avoid overlooking a potential “best” or “better” option. Or, if you really need to make an optimal decision and you have the time and resources available, you may want to consider other methods…methods that follow a more rational approach.