Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Simple comparison polling to create utility functions, published by NunoSempere on November 15, 2021 on The Effective Altruism Forum.
tl;dr:
The Utility Function Extractor is a small web application.
It guides individuals through a process of comparing different pairs of items, by asking them, “How much more valuable is the first option compared to the second one?”
This result is turned into a simple utility function that can be used to compare between all of the items in the set.
You can try the application here.
This technique can be used for comparing moral goods, research outputs, policy initiatives, and more.
Introduction
Say you have a list of items that you want to compare the value of. You just want to know how valuable every item is, in comparison to every other item. Perhaps these items are research documents, or the lives of people at different ages, or personal life improvements.
You could try to come up with one standard unit (QALY, "adjusted research paper", "adjusted life improvement"), but this can be messy.
Instead, all you really need to do is to compare them in pairs. In each case, you say, roughly, "The first item is X% as valuable as the second". If you do this enough times [1], you can produce a simple utility function of all of the items. This would allow you to successfully be able to calculate the value of any two items in the set, even items you haven't directly compared. [2]
One problem with a naive approach is that your preferences might be inconsistent. After valuing A vs. B, B vs. C, and A vs. C, it might be the case that your numbers don't completely match each other. However, you could at least see these discrepancies, and make manual changes upon reflection. You might also want to see the inconsistencies, rather than use some other method that smoothes them out from the beginning (like denominating all items in the same unit.)
I've developed a simple web tool to help people walk through the above steps. I've experimented with this on a few small lists of comparison items. This project is an early exploration of this idea. It would be great to later see much more sophisticated versions.
I originally built it while trying to be less confused about the value of research and about how to elicit information about it. But I recently realized that it also has a more immediate and less speculative application: the EA community could use it to elicit and aggregate GiveWell's moral weights by allowing users to input their own comparisons.
By default, the site asks about GiveWell moral weights. If you instead want to compare research outputs, you can do so here. If you'd instead like to compare your own set of elements, you can do so under "Advanced Options", or you can reach out, and I'm happy to create a page specifically for a given project. Note that I'm saving the user's inputs because I think it might be interesting to aggregate them later.
Potential use cases
Extract comparisons between different moral goods to use as an input to the giant GiveWell spreadsheet.
Poll associates about the value of projects one is considering doing.
Construct a utility function over different types of research outputs.
Construct a utility function over different types of policy initiatives.
Compare the moral weight of different types of sentient beings.
Allocate a prize fund proportionally to the value of entries.
Example
As an example, let's show the app working on comparing various research documents. Right now, we assume that all research is net-positive, and we assume that users feel comfortable estimating how valuable each document is versus each other document.
We're not trying to have a precise definition of "value". Instead, the app leaves this up to the user.
The user is at the start presented with the following screen:
The user then selects, say, t...