@pmartensen Thank you. Yes, were two and working full-time on it! I post most of the project updates on my twitter : https://x.com/alextoussss

@rwijaya thank you!

@vascoamaralgrilo From here (https://docs.google.com/spreadsheets/d/18ROI6dRdKsNfXg5gIyBa1_7eYOjowfbw5n65zkrLnvc/edit#gid=1364064522), bednets provide 0.546 effective person-years of coverage per $ (= 54.6*10^3/(100*10^3)). So a drone costing 200 $ would have to provide 109 person-years of effective coverage (= 200*0.546) to be competitive. In other words, even ignoring maintenance costs, it would have to protect a family of 5 as effectively as bednets for 21.8 years (= 109/5). This seems super optimistic, so I am confused why people are donating so much to your project.

@vascoamaralgrilo

We’re not targeting the individual person market. We’re targeting communities that could cover whole cities with a few drones. Drones travel fast, so can clear of mosquitoes impressive volumes of air in a short amount of time. Our plan entire densely-populated cities mosquito-free. To give you a rough sense of the figures, a drone covering a 2x2 meters square traveling at 10m/s covers 40 cubic meters of air per second. Over a conservative 10 meters of height, that’s 4 square meters/second. For 1000 drones ($200k capital, less than the typical drone light show) you clear a square kilometer in 250 seconds. With a conservative availability factor of 1/4, you cover a square kilometer or 20k people at Paris density for a million dollars. Assuming a very conservative yearly replacement rate, that’s $50/year/person.

The figure is already good enough for the developed world, and with some economies of scale and more realistic estimations it will well be worth it for the developing world!

Please don’t hesitate if you have any other questions, I’d be happy to answer!

@alextouss Thanks for following up, Alex! Your figure of 50 $/person/year is around half of what I estimated, but it still implies that bednets are much better. People with bednets in DRC (the data I provided above was also for DRC) have a 56 % lower malaria mortality (https://docs.google.com/spreadsheets/d/18ROI6dRdKsNfXg5gIyBa1_7eYOjowfbw5n65zkrLnvc/edit#gid=1364064522&range=B93), so the effective cost for bednets would be 3.27 $/person/year (= 1/0.546/0.56). This means bednets would be 15.3 times (= 50/3.27) as cost-effective as drones even assuming these decrease malaria deaths by 100 % and have no development nor maintenance costs. You can argue your cost would decrease due to economies of scale, but there are also other factors which push it up. For example, I think malaria is more prevalent in rural areas, and rural areas in low income countries are much less dense than Paris.

I do not feel like your numbers are conservative as you say (feel free to link to sources supporting that). You say a drone can cover a square of side of side 2 m, but I assume the rotors do not cover an area of 4 m^2! So you cannot use your linear speed to 10 m/s to do the calculation. Also, 10 m/s (36 km/h) is pretty fast! Would people be happy with having thousands of drones flying at these speed in cities? Would it be safe? I assume drones would need to fly relatively close to people, because that is where the mosquitoes are? Maybe it would be better to just fly the drones in the sources of the mosquitoes (bodies of water, I think), but then gene drives just seem way more effective.

@vascoamaralgrilo Bednets aren’t better, they’re in a different category. While they’re cheap, they don’t cover anything outside of bedtime. Although it’s important everyone in the poorest countries can have one, it won’t be enough to get the last 44% coverage needed, which is what we’re targeting.

About the specific figures, the 2x2m comes from the view distance of the sonar. We’re targeting the sub-250g class of drones, which have very light to no regulation around the world. Your typical football is 320 grams and goes up to 40m/s, so our drones would pack 20x less energy. I’m not concerned about city usage.

@alextouss To clarify, would you agree we should fund whatever is most cost-effective at the margin? If bednets save a life for 5 k$, and drones save a life for 76.5 k$ (= 5*10^3*15.3), then one should fund bednets until their marginal cost to save a life reaches 76.5 k$? GiveWell's current cost-effectiveness bar is 10 times that of unconditional cash transfers (https://www.givewell.org/how-we-work/criteria), which means GiveDirectly still looks 1.53 times (= 15.3/10) as cost-effective as your intervention. GiveDirectly's unconditional cash transfers are supe scalable, and I am pretty confident GiveWell has hundreds of millions of $ of room to fund interventions better than GiveDirectly. So one would need to direct hundreds of millions of $ to GiveWell before your project becomes competitive.

@acx-grants Could you explain your reasoning for donating 20 k$ to this project?

@vascoamaralgrilo I'm not sure I get the reason for your hostility. Your donation criteria is yours, and other people have different ones. If you can't see the value of entirely getting rid of mosquitoes in cities for $50/year/person, than I can't do anything for you.

I agree with @alextouss; @vascoamaralgrilo, while I appreciate critiques that are intended to help out projects, I think your stance is unnecessarily combative here, or at least shortsighted/missing the point of Manifund. Manifund is primarily a platform for early stage projects, where there is a lot of information value to be gained from people like Alex trying new and novel things and then telling the world about their results. We don't generally expect interventions at these stages to compare favorably to established interventions like bednets on a spreadsheet (though it's a nice benefit if they do!)

I do also think that mosquito gene drives are extremely promising and I would be excited to see project proposals of that sort on Manifund -- if you are yourself interested in working on this or know of people are, encourage them to apply!

@alextouss Sorry for being too negative. I was assuming the goal of this project was preventing malaria deaths more cost-effectively than the most competitive alternatives (like bednets), but I appreciate others may want to fund the project for other reasons (e.g. because it sounds cool).

Thanks for the the feedback, @Austin . If I was proposing a project, I would find it super helpful if someone pointed out to me there are way more cost-effective interventions. I want to contribute to a better world as much as possible, so I would want to know if the money which would support my project could go towards other interventions that would e.g. save more lives. If I was persuaded by the arguments, I would consider halting the project, returning the money to the donors, and then encourage them to donate to a more promising project.

I agree one should account for the value of information of projects. However, do you think anti-mosquito drones have a realistic chance of being more cost-effective than GiveWell's top charities? If not, there is not much relevant information to be gained? Or are you referring to the value of information which is not related to the cost-effectiveness of the intervention, like Alex getting a better picture of what he wants to do in the future? Are there more cost-effective ways of gaining such other information (for example, for e.g. career plans, checking e.g. 80,000 Hours' career guide (https://80000hours.org/career-guide/))?

I understand Manifund has the goal of supporting early stage projects, I agree it makes sense to support novel interventions, and I personally do not think the platform should be restricted to cost-effective projects. However, I think users should also be welcome to point out whether they think a given project is cost-effective or not.

As a side note, I also think GiveWell's top charities are a pretty low bar. I believe the best animal welfare interventions are 1 k times as cost-effective (https://forum.effectivealtruism.org/posts/vBcT7i7AkNJ6u9BcQ/prioritising-animal-welfare-over-global-health-and#Corporate_campaigns_for_chicken_welfare_increase_nearterm_wellbeing_way_more_cost_effectively_than_GiveWell_s_top_charities).

@vascoamaralgrilo idk, I feel like we're drawing from pretty different worldviews here.

• I don't expect people like Alex to look at a complicated calculation that concludes "and therefore gene drives are 10x as effective as anti-mosquito drones" and think "okay, so I should drop what I'm doing and work on gene drives"

  • Alex might just not believe the calculations -- for plausible reasons! He has a bunch more insight into what's good about drones than an outside observer. I do think anti-mosquito drones have a realistic chance (eg >1%) of being sufficiently cost effective to be part of the fight against malaria

  • His current set of skills sets him up really well for doing this particular project; founder-market fit is super important in making projects go well

• I think you're underrating "because it sounds cool", I guess. To shore this up a bit more, sounding cool is an important factor in getting buzz, being able to raise further funding, get stakeholders to agree to participate, etc.

• I think the general approach of analyzing cost effectiveness just doesn't really make sense for projects at this stage, or is at best one of many different lens. Cost effectieness is a reasonable sanity check, maybe; other than that, I'd look to other signals like founder quality and project velocity

@Austin Thank you for perfectly summing the issue up.

Thanks, @Austin.

I don't expect people like Alex to look at a complicated calculation that concludes "and therefore gene drives are 10x as effective as anti-mosquito drones" and think "okay, so I should drop what I'm doing and work on gene drives"

My Fermi estimate compared Alex's project with Against Malaria Foundation's (AMF's) bednests in DRC, not with gene drives. I am also not expecting Alex to drop the project, but I would appreciate it if @ScottAlexander / @acx-grants could explain their rationale for funding this project. Is the project being funded because it could realistically be funded by GiveWell in the future, i.e. because it could be at least 10 times as cost-effective as donating to people in extreme poverty via GiveDirectly?

Alex might just not believe the calculations -- for plausible reasons! He has a bunch more insight into what's good about drones than an outside observer.

Note my conclusion of AMF's bednets distribution in DRC being 15.3 times as cost-effective as anti-mosquito drones relied on Alex's own calculations. Are you suggesting Alex does not believe in his own calculations, or that my comparison is flawed in some way? I guess the latter, but then it would be nice if you could be more specific. I basically just relied on GiveWell's numbers, which are usually considered quite trustworthy. It is also the case that the real cost-effectiveness tends to be much lower than what is suggested by preliminary results produced by the people proposing the project. One has to control for a thinker's big idea (https://forum.effectivealtruism.org/posts/GW3cxBurTNKHs352S/controlling-for-a-thinker-s-big-idea). So, even if Alex's own calculations are uncertain, I think they will tend to overestimate the cost-effectiveness of the project.

I do think anti-mosquito drones have a realistic chance (eg >1%) of being sufficiently cost effective to be part of the fight against malaria

What do you think is the probability of GiveWell funding Alex's anti-mosquito drones this year? I guess it is around 1 %, and this seems to low to be worth funding. One could contribute to the seed funding of the charities incubated by Charity Entrepreneurship (https://www.givingwhatwecan.org/charities/charity-entrepreneurship-incubated-charities), and I am much more optimistic about their chances of becoming at least as cost-effective as GiveWell's interventions. Charity Entrepreneurship is quite aligned with maximising impact, and their founders go through a very selective process (e.g. I am pretty confident they would understand the concept of marginal cost-effectiveness).

His current set of skills sets him up really well for doing this particular project; founder-market fit is super important in making projects go well

I agree. However, I am thinking a project going well is a necessary rather than sufficient condition for funding it. If a project has the main goal of saving/improving lives, it (or a future iteration of it) still has to do it more cheaply than the best alternatives (like bednets). To illustrate, I am quite confident GiveDirectly makes unconditional cash transfers go well, but I think people wanting to save/improve lives as much as possible had better donate to GiveWell's funds, which fund projects at least 10 times as cost-effective as GiveDirectly.

I think you're underrating "because it sounds cool", I guess. To shore this up a bit more, sounding cool is an important factor in getting buzz, being able to raise further funding, get stakeholders to agree to participate, etc.

As above, I agree these considerations are relevant, but they are not enough. PlayPump sounded like a cool cost-effective way of supplying water to people in low income countries, and it attracted lots of funding on this basis, but it turned out to be way less cost-effective that the best alternatives (https://forum.effectivealtruism.org/topics/playpump). I believe greater scrutiny would have revealed this earlier.

I think the general approach of analyzing cost effectiveness just doesn't really make sense for projects at this stage, or is at best one of many different lens. Cost effectieness is a reasonable sanity check, maybe; other than that, I'd look to other signals like founder quality and project velocity

I think cost-effectiveness analyses make sense for early stage projects if they are easy to produce, and I suppose it was quite easy for Alex to get the estimate of 50 $/person/year in his 1st comment in this thread. In addition, I would say it would be worth it to spend more time coming up with a better estimate, as this would very much inform the requirements of the drone. It may be that the requirements for the drones to save lives as cost-effectively as GiveWell's interventions are very unrealistic (e.g. the cost per drone would have to be unreasonably low), which may prompt rethinking or dropping the project.

I agree other considerations besides cost-effectiveness are also relevant, but I feel like you are underweighting it because it seems quite quantifiable in the case of Alex's project (as Alex nicely illustrated). Elie Hassenfeld, who is the CEO of GiveWell (whose evaluations are considered the gold-standard in global health and development), said (https://podcast.clearerthinking.org/episode/096/elie-hassenfeld-why-it-s-so-hard-to-have-confidence-that-charities-are-doing-good/):

GiveWell cost- effectiveness estimates are not the only input into our decisions to fund malaria programs and deworming programs, there are some other factors, but they're certainly 80% plus of the case.

GiveWell said (https://forum.effectivealtruism.org/posts/CDt5ShpdABZRn8Tvi/my-quick-thoughts-on-donating-to-ea-funds-global-health-and?commentId=CXspdihsLLSepbyjC):

The numerical cost-effectiveness estimate in the spreadsheet is nearly always the most important factor in our recommendations, but not the only factor. That is, we don’t solely rely on our spreadsheet-based analysis of cost-effectiveness when making grants. 

I assume I am also less optimistic than you about Alex. I get the impression Alex may want to go ahead with the project even if he was certain it would be less cost-effective than GiveWell's interventions, and his project absorbed funding which would otherwise go to GiveWell's interventions, which I think would be bad. I am also not sure Alex understands the concept of marginal cost-effectiveness based on his 2nd comment in this thread.

@vascoamaralgrilo

Bednets serve as a barrier against mosquitoes during sleep. Our goal is their eradication.

Your extensive arguments reduce analysis to a single metric, cost-effectiveness, to the point of being comical to the average reader. Most would happily pay $5/month to rid their city of mosquitoes instead of relying on nets. I'm not sure why you fail to see that.

@vascoamaralgrilo shrug, once again, I think you're missing the point of Manifund (early stage interventions look very different than established ones; charity entrepreneurship charities might be a better comparison) and also missing the point of ACX Grants (which is mostly not to compete against GiveWell - see Scott's writeups and look at the other ACX Grants made).

I'm unfortunately not sure how to orient this conversation to be more productive here. I'd be open to a bet or prediction market of some kind like "will Alex raise further funding from an EA funder" if that seems cruxy to you. Otherwise I encourage you to come to Manifest, where both Alex and I will be; perhaps talking it out in person would be helpful!

I'd be open to a bet or prediction market of some kind like "will Alex raise further funding from an EA funder" if that seems cruxy to you.

@Austin , what do you think about the following bet. If Alex is not funded by Charity Entrepeneurship (one can apply to their incubation program with one's own idea) nor GiveWell until 1 year from now (i.e. until the end of 1 May 2025) in the context of his drone project, you send me 100 $. Otherwise, I send you 900 $ (= (1 - 0.1)/0.1*100), as I think that is less than 10 % likely.

Okay, I have set up this prediction market; let's move the discussion on operationalization there. I'm open to a cash bet of that size once we've figured out terms.

@Dark-shark-420 Thank you!

@Bernars Directly answering to your email

@Guyrus- Thanks a lot!

@Emile Hahaha, thank you!

@dimitris Thank you !

@Pingu2k Thank you for your help!

@guenael

We've got a 40db SNR from emitter to receiver at 1m with an integration period of 25microseconds.

We have 16 transmitters in a phased array, so with focusing gains we have SNR*16*16.

100 receivers, SNR gains in SNR*100 as noise power adds-up in N and signal power adds-up in N^2

We correlate on a 20 periods-long (17cm) window. Signal adds-up in N^2 and noise in N again.

We're really close to measuring a mosquito's sonar cross section. But, assuming wings 5mm long and 2mm wide, we can estimate it at 10e-6 m^2. A conservative assumption could be around 1e-6 m^2

From the radar range equation : ((10**(40/10))*16*16*100*20*1e-6/((4*3.14)**2))**(1/4) = 2.4 meters.

It turns out, the radar range equation being in R^(1/4) really helps. It stops growing so quickly that even big cross-section differences have a limited effect on the range. Plus, the physics of SNR are really nice with very large transmit and receiver array.

About the drone turbulence I'm not sure it would have a very significant effect in the ultrasonic band we use (40khz). It probably is more of a problem at 20khz than at 40, and there are a lot of ways we could filter it : either electronically, by looking at the spatial and time distribution of the noise, or mechanically by moving it to a region where airflow isn't that disturbed.

The main problem could be the propellers vibrations. But, because we know what the frequencies are (propeller's RPM are controlled by our flight controller) we can dynamically adapt a very narrow cut-band notch filter to ensure it doesn't make its way to our CFAR detection. Flight controllers use the same method to filter propeller noise into gyroscope reading.

Happy to answer any other questions! Invited you on LinkedIn.

@Jonas-Hyllengren Thanks a lot ! Your contribution will definitely help.

@saulmunn

1. Hard to be sure about it :/

2. That’s already been studied, and the general consensus seems to be that mosquitoes are a small part of the alimentation of their predators, while they cause a disproportionate amount of harm to the human population.

@saulmunn thanks a lot for your encouragements :-)

@davekasten We’re mainly targeting the developing world for the moment, but there’s no reason for us to restrict our reach! Thank you for your support.