About two months ago, Michael Plant, Joel McGuire and Clare Donaldson from the Happier Lives Institute posted on this forum about Using Subjective Well-Being to Estimate the Moral Weights of Averting Deaths and Reducing Poverty. I wrote some feedback on the post and Michael asked me to share it here.

These are my own views but I'm very grateful to my colleagues on the Founders Pledge research and advisory teams for comments and discussion.

Overall thoughts

The trade-off between saving lives and increasing consumption is really important to prioritisation in global health and development and I think subjective well-being (SWB) offers potentially really useful tools for making trade-offs like this, so I’m really excited to see this post. This post functions very well as an initial proof of concept of using SWB in cost-effectiveness analyses and I think it’s a strong early step in applying well-being analysis. The analysis impressively comes to reasonable conclusions, often with only poor quality data available. I’m excited to see this methodology develop further.

The post and guesstimate model are clear and easy to understand. I was especially impressed by the presentation of the guesstimate model. These easily get unwieldy but this is extremely clear and easy to follow.

I have one major comment and a few minor comments. Most of the minor comments are best interpreted as things to think about in future work rather than direct criticisms of the post.

One major comment

Beware the difference between an expected value of a ratio and a ratio of expected values. You calculate the expected value of a ratio but I think you should instead look at the ratio of expected values. The ratio of expected values is about 40% lower than the expected ratio.

A simple illustrative example

Suppose there are two options, A and B, and two scenarios, 1 and 2. You are uncertain about which scenario is actual but you know that they are equally likely. Suppose that you can get the following pay-offs by choosing option A or B in a scenario 1 or 2:

\begin{matrix} Scenerio 1 pay-off & Scenerio 2 pay-off & Expected value A & 1 & 4 & 2.5 B & 4 & 2 & 3 \frac{A}{B} & \frac{1}{4} & 2 & \frac{9}{8} > 1 \frac{B}{A} & 4 & \frac{1}{2} & \frac{9}{4} > 1 \end{matrix}

Which option should we choose? Ratios are helpful: if x/y > 1, then we know that x > y (as long as x and y are positive). $E (A / B) > 1$ , so should we expect A to be better than B and choose A over B? No. Note that $E (B / A)$ is also greater than...

Moral weight

Further reading