What this is: Value of information BOTEC for Development Innovation Lab (DIL) RCT of vouchers for water chlorination. Key parameters are in light blue.

Not used in calculations; for interpretation only

Average of rough CE estimates across countries where water chlorination CE is above ~6x cash

Average of rough CE estimates across countries where water chlorination CE is above ~6x cash

Average of rough CE estimates across countries where water chlorination CE is above ~6x cash

For the overall average, we place a 50% weight on the cost-effectiveness of water chlorination via Dispensers for Safe Water (DSW), compared to 25% weight for the other two interventions, since the implementation infrastructure is already in place for DSW and thus that program may be easier to scale. For more information on DSW, see this page: https://www.givewell.org/research/grants/evidence-action-dispensers-for-safe-water-January-2022

Guess. Using similar value to other value of information BOTECs.

Guess. Expected cost-effectiveness of counterfactual use of funds in 2025.

Top charities cost-effectiveness analysis

This assumes that the cost-effectiveness of opportunities decays over a 10-year period. Using similar value to other value of information BOTECs.

Guess. If we didn't fund the evaluation, we would use our current best guess of cost-effectiveness and recommend funding to areas that are above the cost-effectiveness of counterfactual programs we might recommend funding (our current bar for recommending funding is 10x cash).

Conservative guess, see cell B10. We use a lower value than the 13.7x cash calculated in cell B10 to account for uncertainty in that estimate and to avoid overstating the cost-effectiveness of the RCT.

If the evaluation provides a negative update on cost-effectiveness, we would reduce the amount we recommend to water chlorination interventions since there would be fewer gaps that are above our bar.

Guess. Assuming opportunities estimated to be 10-13x cash are now below our bar of 10x cash, such that the average CE of water chlorination interventions falls from ~10x cash to 8x cash.

Guess. Our bar was 8x cash when we approved a January 2022 grant to DSW; since we now have a 10x cash bar, this effectively means that water chlorination interventions have to become more cost-effective to "stay the same" (i.e. meet our bar).

Guess. If we get confirmation of our current cost-effectiveness estimates, we would likely recommend funding opportunities currently estimated to be at least 10x cash. It is also possible that we may want to recommend more funding to these programs, even if our cost-effectiveness best guess stays the same, due to the increased confidence in our estimates. This would depend on our level of confidence in the evaluation results.

Conservative guess, see cell B10. We use a lower value than the 13.7x cash calculated in cell B10 to account for uncertainty in that estimate and to avoid overstating the cost-effectiveness of the RCT.

Conservative estimate. If we get a positive update on cost-effectiveness, we're likely to direct more funding to water chlorination interventions, since even more may meet our bar and we'd be more confident in the underlying evidence.

Guess. Assuming opportunities estimated to be 7-10x cash are now at/above our bar, such that average cost-effectiveness of water chlorination interventions moves from being ~10x cash to 12x cash.

Rough guess. On the one hand, we think this is likely to be a well-powered, well-executed RCT, which makes us think we should reduce this adjustment from -20%. On the other hand, updating incorrectly would be very costly given how important this trial is to our overall CE estimates and future funding of water quality interventions, which makes us think it should be higher. We believe these considerations net out to around -20%.

Given the study authors and potential interest from other funders, we believe it is reasonable to assume that some version of this study might be funded within a few years.

Guess. We have increased this adjustment from our default 20% because mortality studies are rare, particularly in the water, sanitation, and hygiene (WASH) field.