Thank @Vasco Grilo you for your thoughtful comments. Appreciate it!
I don’t think you’ve missed anything. I think you’ve identified a very valid critique of the assumptions I used to express cost-effectiveness as a cost per DALY averted range. Expressing the welfare ranges in units of seconds or years is a great way of bringing this out – so thank you for doing that.
Some comments:
If I were to rebuild the cost-effectiveness model, with the benefit of hindsight (and more time), I’d have probably used a probabilistic rather than deterministic variable for the assumption converting the % improvement in the human welfare range (for one year) that is equivalent to averting a DALY.
I’m pretty sure assumption feeds through linearly into the $/DALY results. So if you believed an assumption of 5% of human welfare range was more appropriate than 50%, you could divide the 5th and 95th percentiles of the cost per DALY averted range.
The formal sensitivity tests I did suggest the conclusions of how this intervention looks compared to the most promising GHD and animal welfare interventions wouldn’t change with ‘relatively small’ adjustments to the assumptions needed to convert results into DALY space (e.g. doubling the fish welfare range relative to humans and assuming averting a DALY is equivalent to a human intervention that raises human welfare by 10% of the human welfare range for 1 year).
I think once you start making bigger adjustments to these assumptions, you can run into the risk of being criticised for placing too much moral value on short-duration but high intensity suffering. I don’t think we have good empirical evidence to support any particular assumption here.
The moral value section of the results more formally illustrates how the fish stunning intervention compares to various $/DALY benchmarks depending on the moral value you might assign to improving a year of fish life via the intervention relative to averting a DALY.
I don’t think the narrative expressed in the executive summary would change even if I were to change the assumption on the moral value of averting intense suffering relative to extending healthy lifespan.
While I think there is a lot of value in trying to place results into a ‘common currency’, I think this is also a good reason why cost per DALY averted numbers should always be treated with some caution (there is will always be moral value judgements there, some of which may be objectionable). I think it’s valuable important to look at a number of different metrics (number of animals affected, amount of time affected) to assess how promising an animal welfare intervention looks.
Thank @Vasco Grilo you for your thoughtful comments. Appreciate it!
I don’t think you’ve missed anything. I think you’ve identified a very valid critique of the assumptions I used to express cost-effectiveness as a cost per DALY averted range. Expressing the welfare ranges in units of seconds or years is a great way of bringing this out – so thank you for doing that.
Some comments:
If I were to rebuild the cost-effectiveness model, with the benefit of hindsight (and more time), I’d have probably used a probabilistic rather than deterministic variable for the assumption converting the % improvement in the human welfare range (for one year) that is equivalent to averting a DALY.
I’m pretty sure assumption feeds through linearly into the $/DALY results. So if you believed an assumption of 5% of human welfare range was more appropriate than 50%, you could divide the 5th and 95th percentiles of the cost per DALY averted range.
The formal sensitivity tests I did suggest the conclusions of how this intervention looks compared to the most promising GHD and animal welfare interventions wouldn’t change with ‘relatively small’ adjustments to the assumptions needed to convert results into DALY space (e.g. doubling the fish welfare range relative to humans and assuming averting a DALY is equivalent to a human intervention that raises human welfare by 10% of the human welfare range for 1 year).
I think once you start making bigger adjustments to these assumptions, you can run into the risk of being criticised for placing too much moral value on short-duration but high intensity suffering. I don’t think we have good empirical evidence to support any particular assumption here.
The moral value section of the results more formally illustrates how the fish stunning intervention compares to various $/DALY benchmarks depending on the moral value you might assign to improving a year of fish life via the intervention relative to averting a DALY.
I don’t think the narrative expressed in the executive summary would change even if I were to change the assumption on the moral value of averting intense suffering relative to extending healthy lifespan.
While I think there is a lot of value in trying to place results into a ‘common currency’, I think this is also a good reason why cost per DALY averted numbers should always be treated with some caution (there is will always be moral value judgements there, some of which may be objectionable). I think it’s valuable important to look at a number of different metrics (number of animals affected, amount of time affected) to assess how promising an animal welfare intervention looks.