Effective Altruism Through Advertising Vegetarianism?

Abstract: If you value the welfare of nonhuman animals from a consequentialist perspective, there is a lot of potential for reducing suffering by funding the persuasion of people to go vegetarian through either online ads or pamphlets. In this essay, I develop a calculator for people to come up with their own estimates, and I personally come up with a cost-effectiveness estimate of $0.02 to $65.92 needed to avert a year of suffering in a factory farm. I then discuss the methodological criticism that merits skepticism of this estimate and conclude by suggesting (1) a guarded approach of putting in just enough money to help the organizations learn and (2) the need for more studies should be developed that explore advertising vegetarianism in a wide variety of media in a wide variety of ways, that include decent control groups.



I start with the claim that it’s good for people to eat less meat, whether they become vegetarian—or, better yet, vegan—because this means less nonhuman animals are being painfully factory farmed. I’ve defended this claim previously in my essay “Why Eat Less Meat?”. I recognize that some people, even those who consider themselves effective altruists, do not value the well-being of nonhuman animals. For them, I hope this essay is interesting, but I admit it will be a lot less relevant.

The second idea is that it shouldn’t matter who is eating less meat. As long as less meat is being eaten, less animals will be farmed, and this is a good thing. Therefore, we should try to get other people to also try and eat less meat.

The third idea is that it also doesn’t matter who is doing the convincing. Therefore, instead of convincing our own friends and family, we can pay other people to convince people to eat less meat. And this is exactly what organizations like Vegan Outreach and The Humane League are doing. With a certain amount of money, one can hire someone to distribute pamphlets to other people or put advertisements on the internet, and some percentage of people who receive the pamphlets or see the ads will go on to eat less meat. This idea and the previous one should be uncontroversial for consequentialists.

But the fourth idea is the complication. I want my philanthropic dollars to go as far as possible, so as to help as much as possible. Therefore, it becomes very important to try and figure out how much money it takes to get people to eat less meat, so I can compare this to other estimations and see what gets me the best “bang for my buck”.

Other Estimations

I have seen other estimates floating around the internet that try to estimate the cost of distributing pamphlets, how many conversions each pamphlet produces, and how much less meat is ate via each conversion. Brian Tomasik calculates $0.02 to $3.65 [PDF] per year of nonhuman animal suffering prevented, later $2.97 per year, and then later $0.55 to $3.65 per year.

Jess Whittlestone provides statistics that reveal an estimate of less than a penny per year[1].

Effective Animal Activism, a non-profit evaluator for animal welfare charities, came up with an estimate [Excel Document] of $0.04 to $16.60 per year of suffering averted, that also takes into account a variety of additional variables, like product elasticity.

Jeff Kaufman uses a different line of reasoning, by estimating how many vegetarians there are and guessing how many of them came via pamphlets, estimates it would take $4.29 to $536 to make someone vegetarian for one year. Extrapolating from that using at a rate of 255 animals saved per year and a weighted average of 329.6 days lived per animal (see below for justification of both assumptions), would give $0.02 to $1.90 per year of suffering averted[2].

A third line of reasoning, also by Jeff Kaufman, was to measure the amount of comments on the pro-vegetarian websites advertised in these campaigns and found that 2-22% of them were about an intended behavior change (eating less meat, going vegetarian, or going vegan), depending on the website. I don’t think we can draw any conclusions from this, but it’s interesting.

To make my calculations, I decided to make a calculator. Unfortunately, I can’t embed it here, so you’d have to open it in a new tab as a companion piece.

I’m going to start by using the following formula: Years of Suffering Averted per Dollar = (Pamphlets /​ dollar) * (Conversions /​ pamphlet) * (Veg years /​ conversion) * (Animals saved /​ veg year) * (Days lived /​ animal)

Now, to get estimations for these variables.

Pamphlets Per Dollar

How much does it cost to place the advertisement, whether it be the paper pamphlet or a Facebook advertisement? Nick Cooney, head of the Humane League, says the cost-per-click of Facebook ads is 20 cents.

But what about the cost per pamphlet? This is more of a guess, but I’m going to go with <a href=”″>Vegan Outreach’s suggested donation of $0.13 per “Compassionate choices” booklet.

However, it’s important to note that this cost must also include opportunity cost—leafleters must forego the ability to use that time to work a job. This means I must include an opportunity cost of say $8/​hr on top of that, making the actual cost $0.27 assuming a pamphlet is given out each minute of volunteer time, meaning 3.7 people are reached per dollar from pamphlets. For Facebook advertisements, the opportunity cost is trivial.

Conversions Per Pamphlet

This is the estimate with the biggest target on it’s head, so to speak. How many people do we get to actually change their behavior with a simple pamphlet or Facebook advertisement? Right now, we have three lines of evidence:

Facebook Study

Humane League did A $5000 Facebook advertisement campaign. They bought ads that look like this...

...and sent people to websites (like this one or this one) with auto-playing videos that start playing and show the horrors of factory farming.

Afterward, there was another advertisement run to people who “liked” the video page, offering a 1 in 10 chance of winning a free movie ticket in order to take a survey. Everyone who emailed in asking for a free vegetarian starter kit were also emailed a survey. 104 people took the survey and there were 32 reported vegetarians[3] and 45 people reported, for example, that their chicken consumption decreased “slightly” or “significantly”.

7% of visitors liked the page and 1.5% of visitors ordered a starter kit. Assuming all the other people went away from the video not changing their consumption, this survey would lead us to (very tenuously) think about 2.6% of people seeing the video will become a vegetarian[4].

(Here’s the results of the survey in PDF.)

Pamphlet Study

A second study discussed in “The Powerful Impact of College Leafleting (Part 1)” and “The Powerful Impact of College Leafleting: Additional Findings and Details (Part 2)” looked specifically at pamphlets.

Here, Humane League staff visited two large East Coast state schools and distributed leaflets. They then returned two months later and surveyed people walking by. Those who remember receiving a leaflet earlier were counted. They found about 2% of those receiving a pamphlet went vegetarian.

Vegetarian Years Per Conversion

But once a pamphlet or Facebook advertisement captures someone, how long will they stay vegetarian? One survey showed vegetarians refrain from eating meat for an average of 6 years or more. Another study I found says 93% of vegetarians stay vegetarian for at least three years.

Animals Saved Per Vegetarian Year

And once you have a vegetarian, how many animals do they save per year? CountingAnimals says 406 animals saved per year.

The Humane League suggests 28 chickens, 2 egg industry hens, 18 beef cow, 12 pig, 1 turkey, and 130 dairy cow per year (total = 31.66 animals), and does not provide statistics on fish. This agrees with CountingAnimals on non-fish totals.

Days Lived Per Animal

One problem, however, is that saving a cow that could suffer for years is different from saving a chicken that suffers for only about a month. Using data from Farm Sanctuary plus World Society for the Protection of Animals data on fish [PDF], I get this table:

Animal Number Days Alive
Chicken (Meat) 28 42
Chicken (Egg) 2 365
Cow (Beef) 0.125 365
Cow (Milk) 0.033 1460
Fish 225 365

This makes the weighted average 329.6 days[5].

Accounting For Biases

As I said before, our formula was Years of Suffering Averted = (Pamphlets /​ dollar) * (Conversions /​ pamphlet) * (Veg years /​ conversion) * (Animals saved /​ veg year) * (Days lived /​ animal).

Let’s plug these values in… Years of Suffering Averted per Dollar = 5 * 0.02 * 3 * 255.16 * 329.6/​365 = 69.12.

Or, assuming all this is right (and that’s a big assumption), it would cost less than 2 cents to prevent a year of suffering on a factory farm by buying vegetarians.

I don’t want to make it sound like I’m beholden to this cost estimate or that this estimate is the “end all, be all” of vegan outreach. Indeed, I share many of the skepticisms that have been expressed by others. The simple calculation is… well… simple, and it needs some “beefing up”, no pun intended. Therefore, I also built a “complex calculator” that works on a much more complex formula[6] that is hopefully correct[7] and will provide a more accurate estimation.

The big, big deal for the surveys is concern for bias. The most frequently mentioned bias is social desirability bias, or people who say they reduced meat just because they want to please the surveyor or look like a good person, which actually happens a lot more on surveys than we’d like.

To account for this, we’ll have to figure out how inflated answers are because of this bias and then scale the answers down by that amount. Nick Cooney who says that he’s been reading studies that about 25% to 50% of people who say they are vegetarian actually are, though I don’t yet have the citations. Thus, if we find out that an advertisement creates two meat reducers, we’d scale that down to one reducer if we’re expecting a 50% desirability bias.

The second bias that will be a problem for us is non-response bias, as those who don’t reduce their diet are less likely to take the survey and therefore less likely to be counted. This is especially true in the Facebook study, which only measures people who “liked” or requested a starter kit, showing some pro-vegetarian affiliation.

We can balance this out by assuming everyone who didn’t take the survey went on to have no behavior change whatsoever. Nick Cooney’s Facebook Ad Survey is for the 7% of people who liked the page (and then responded to the survey), and obviously those who liked the page are more likely to reduce their consumption. I chose an optimistic value of 90% to consider the survey completely representative of the 7% who liked the page, and then a bit more for those who reduced their consumption but did not like the page. My pessimistic value was 95%, assuming everyone who did not like the survey went unchanged and assuming a small response bias among those who liked the page but chose not to take the survey.

For the pamphlets, however, there should be no response bias since the entire population of college students was surveyed from randomly, and no one was said to reject taking the survey.

Additional People Are Being Reached

In the Facebook survey, those who said they reduced their meat consumption were also asked if they influenced any of their friends and family to also reduce eating meat, and found that they usually produced 0.86 additional reducers.

This figure seems very high, but I do strongly expect the figure to be positive—people who reduce eating meat will talk about it sometimes, essentially becoming free advertisements. I’d be very surprised if they ended up being a net negative.

Accounting for Product Elasticity

Another way to boost the effectiveness of the estimate is to be more accurate about what happens when someone stops eating meat. The change isn’t from the actual refusal to eat, but rather from the reduced demand for meat, which leads to a reduced supply. Following the laws of economics, however, this reduction won’t necessarially be one-for-one, but rather depend on the elasticity of product demand and supply. By getting this number, we can find out how much meat is reduced for every meat not demanded.

My guesses in the calculator come from the following sources, some of which are PDFs: Beef #1, Beef #2, Dairy #1, Dairy #2, Pork #1, Pork #2, Egg #1, Egg #2, Poultry, Salmon, and for all fish.

Putting It All Together

Implementing the formula on the calculator, we end up with an estimate of $0.03 to $36.52 to reduce one year of suffering on a factory farm based on the Facebook ad data and an estimate of $0.02 to $65.92 based on the pamphlet data.

Of course, many people are skeptical of these figures. Perhaps surprisingly, so am I. I’m trying to strike a balance between being an advocate of vegan outreach as a very promising path for making the world a better place, while not losing sight of the methodological hurdles that have not yet been met, and open to the possibility that I’m wrong about this.

The big methodological elephant in the room is that my entire cost estimate depends on having a plausible guess for how likely someone is to change their behavior based on seeing an advertisement.

I feel slightly reassured because:

  1. There are two surveys for two different media, and they both provide estimates of impact that agree with each other.

  2. These estimates also match anecdotes from leafleters about approximately how many people come back and say they went vegetarian because of a pamphlet.

  3. Even if we were to take the simple calculator and drop the “2% chance of getting four years of vegetarianism” assumption down to, say, a pessimistic “0.1% chance of getting one year” conversion rate, the estimate is still not too bad -- $0.91 to avert a year of suffering.

  4. More studies are on the way. Nick Cooney is going to do a bunch more to study leaflets, and Xio Kikauka and Joey Savoie have publicly published some survey methodology [Google Docs].

That said, the possibility for desirability bias in the survey is a large concern as long as the surveys continue to be from overt animal welfare groups and continue to clearly state that they’re looking for reductions in meat consumption.

Also, so long as surveys are only given to people that remember the leaflet or advertisement, there will be a strong possibility of response bias, as those who remember the ad are more likely to be the ones who changed their behavior. We can attempt to compensate for these things, but we can only do so much.

Furthermore, and more worrying, there’s a concern that the surveys are just measuring normal drift in vegetarianism, without any changes being attributable to the ads themselves. For example, imagine that every year, 2% of people become vegetarians and 2% quit. Surveying these people at random and not capturing those who quit will end up finding a 2% conversion rate.

How can we address these? I think all three problems can be solved with a decent control group, whether it be a group of people that receive a leaflet not about vegetarianism, or no leaflet at all. Luckily, Kikauka and Savoie’s survey intend to do just that.

Jeff Kaufman has a good proposal for a survey design I’d like to see implemented in this area.

Market Saturation and Diminishing Marginal Returns?

Another concern is that there are diminishing marginal returns to these ads. As the critique goes, there are only so many people that will be easily swayed by the advertisement, and once all of them are quickly reached by Facebook ads and pamphlets, things will dry up.

Unlike the others, I don’t think this criticism works well. After all, even if it were true, it still would be worthwhile to take the market as far as it will go, and we can keep monitoring for saturation and find the point where it’s no longer cost-effective.

However, I don’t think the market has been tapped up yet at all. According to Nick Cooney [PDF], there are still many opportunities in foreign markets and outside the young, college kid demographic.

The Conjunction Fallacy?

The conjunction fallacy is a classic fallacy that reminds us that no matter what, the chance of event A happening can never be smaller than the chance of event A happening, followed by event B. For example, the probability that Linda is a bank teller will always be larger than (or equal to) the probability that Linda is a bank teller and a feminist.

What does this mean for vegetarian outreach? Well, for the simple calculator, we’re estimating five factors. In the complex calculator, we’re estimating 90 factors. Even if each factor is 99% likely to be correct, the chance that all five are right is 95%, and the chance that all 50 are right is only 60%. If each factor is only 90% likely to be correct, the complex calculator will be right with a probability of 0.5%!

This is a cause for concern, but I don’t think there’s any way around this. It’s just an inherent problem with estimation. Hopefully we’ll be balanced by (1) using the different bounds and (2) hoping underestimates and overestimates will cancel each other out.

Conversion and The 100 Yard Line

Something we should take into account that helps the case for this outreach rather than hurts it is the idea that conversions aren’t binary—someone can be pushed by the ad to be more likely to reduce their meat intake as opposed to fully converted. As Brian Tomasik puts it:

Yes, some of the people we convince were already on the border, but there might be lots of other people who get pushed further along and don’t get all the way to vegism by our influence. If we picture the path to vegism as a 100-yard line, then maybe we push everyone along by 20 yards. 15 of people cross the line, and this is what we see, but the other 45 get pushed closer too. (Obviously an overly simplistic model, but it illustrates the idea.)

This would be either very difficult or outright impossible to capture in a survey, but is something to take into account.

Three Places I Might Donate Before Donating to Vegan Outreach

When all is said and done, I like the case for funding this outreach. However, I think there are three other possibilities along these lines that I find more promising:

Funding the research of vegan outreach: There needs to be more and higher-quality studies of this before one can feel confident enough in the cost-effectiveness of this outreach. However, initial results are very promising, and the value of information of more studies is therefore very high. Studies can also find ways to advertise more effectively, increasing the impact of each dollar spent. Right now, however, it looks like all ongoing studies are fully funded, but if there were opportunities to fund more, I would jump on it.

Funding Effective Animal Activism: EAA is an organization pushing for more cost-effectiveness in the domain of nonhuman animal welfare and is working to further evaluate what opportunities are the best, Givewell-style. Giving them more money can potentially attract a lot more attention to this outreach, and get it more scrutiny, research, and money down the line.

Funding Centre for Effective Altruism: Overall, it might just be better to get more people involved in the idea of giving effectively, and then getting them interested in vegan outreach, among other things.


Vegan outreach is a promising, though not fully studied, method of outreach that deserves both excitement and skepticism. Should one put money into it? Overall, I’d take a guarded approach of putting in just enough money to help the organizations learn, develop better cost-effective measurements and transparency, and become more effective. It shouldn’t be too long before this area will become studied well enough to have good confidence in how things are doing.

More studies should be developed that explore advertising vegetarianism in a wide variety of media in a wide variety of ways, with decent control groups.

I look forward to seeing how this develops. Don’t forget to play around with my calculator.



[1]: Cost effectiveness in years of suffering prevented per dollar = (Pamphlets /​ dollar) * (Conversions /​ pamphlet) * (Veg years /​ conversion) * (Animals saved /​ veg year) * (Years lived /​ animal).

Plugging in 80K’s values… Cost effectiveness = (Pamphlets /​ dollar) * 0.01 to 0.03 * 25 * 100 * (Years lived /​ animal)

Filling in the gaps with my best guesses… Cost effectiveness = 5 * 0.01 to 0.03 * 25 * 100 * 0.90 = 112.5 to 337.5 years of suffering averted per dollar
I personally think 25 veg-years per conversion on average is possible but too high; I personally err from 4 to 7.
[2]: I feel like there’s an error in this calculation or that Kaufman might disagree with my assumptions of number of animals or days per animal, because I’ve been told before that these estimates with this method are supposed to be about an order of magnitude higher than other estimates. However, I emailed Kaufman and he seemed to not find any fault with the calculation, though he does think the methodology is bad and the calculation should not be taken at face value.
[3]: I calculated the number of vegetarians by eyeballing about how many people said they no longer eat fish, which I’d guess only a vegetarian would be willing to give up.
[4]: 32 vegetarians /​ 104 people = 30.7%. That population is 8.5% (7% for likes + 1.5% for the starter kit) of the overall population, leading to 2.61% (30.7% * 8.5%).
[5]: Formula is [(Number Meat Chickens)(Days Alive) + (Number Egg Chickens)(Days Alive) + (Number Beef Cows)(Days Alive) + (Number Milk Cows)(Days Alive) + (Number Fish)(Days Alive)] /​ (Total Number Animals). …Plugging things in: [(28)(42) + (2)(365) + (0.125)(365) + (0.033)(1460) + (225)(365)] /​ 255.16] = 329.6 days

Cost effectiveness in amount of days prevented per dollar = (People Reached /​ Dollar + (People Reached /​ Dollar * Additional People Reached /​ Direct Reach * Response Bias * Desirability Bias)) * Years Spent Reducing * (((Percent Increasing Beef * Increase Value) + (Percent Staying Same with Beef * Staying Same Value) + (Percent Decreasing Beef Slightly * Decrease Slightly Value) + (Percent Decreasing Beef Significantly * Decrease Significantly Value) + (Percent Eliminating Beef * Elimination Value) + (Percent Never Ate Beef * Never Ate Value)) * Normal Beef Consumption * Beef Elasticity * (Average Beef Lifespan + Days of Suffering from Beef Slaughter)) + (((Percent Increasing Dairy * Increase Value) + (Percent Staying Same with Dairy * Staying Same Value) + (Percent Decreasing Dairy Slightly * Decrease Slightly Value) + (Percent Decreasing Dairy Significantly * Decrease Significantly Value) + (Percent Eliminating Dairy * Elimination Value) + (Percent Never Ate Dairy * Never Ate Value)) * Normal Dairy Consumption * Dairy Elasticity * (Average Dairy Lifespan + Days of Suffering from Dairy Slaughter)) + (((Percent Increasing Pig * Increase Value) + (Percent Staying Same with Pig * Staying Same Value) + (Percent Decreasing Pig Slightly * Decrease Slightly Value) + (Percent Decreasing Pig Significantly * Decrease Significantly Value) + (Percent Eliminating Pig * Elimination Value) + (Percent Never Ate Pig * Never Ate Value)) * Normal Pig Consumption * Pig Elasticity * (Average Pig Lifespan + Days of Suffering from Pig Slaughter)) + (((Percent Increasing Broiler Chicken * Increase Value) + (Percent Staying Same with Broiler Chicken * Staying Same Value) + (Percent Decreasing Broiler Chicken Slightly * Decrease Slightly Value) + (Percent Decreasing Broiler Chicken Significantly * Decrease Significantly Value) + (Percent Eliminating Broiler Chicken * Elimination Value) + (Percent Never Ate Broiler Chicken * Never Ate Value)) * Normal Broiler Chicken Consumption * Broiler Chicken Elasticity * (Average Broiler Chicken Lifespan + Days of Suffering from Broiler Chicken Slaughter)) + (((Percent Increasing Egg * Increase Value) + (Percent Staying Same with Egg * Staying Same Value) + (Percent Decreasing Egg Slightly * Decrease Slightly Value) + (Percent Decreasing Egg Significantly * Decrease Significantly Value) + (Percent Eliminating Egg * Elimination Value) + (Percent Never Ate Egg * Never Ate Value)) * Normal Egg Consumption * Egg Elasticity * (Average Egg Lifespan + Days of Suffering from Egg Slaughter)) + (((Percent Increasing Turkey * Increase Value) + (Percent Staying Same with Turkey * Staying Same Value) + (Percent Decreasing Turkey Slightly * Decrease Slightly Value) + (Percent Decreasing Turkey Significantly * Decrease Significantly Value) + (Percent Eliminating Turkey * Elimination Value) + (Percent Never Ate Turkey * Never Ate Value)) * Normal Turkey Consumption * Turkey Elasticity * (Average Turkey Lifespan + Days of Suffering from Turkey Slaughter)) + (((Percent Increasing Farmed Fish * Increase Value) + (Percent Staying Same with Farmed Fish * Staying Same Value) + (Percent Decreasing Farmed Fish Slightly * Decrease Slightly Value) + (Percent Decreasing Farmed Fish Significantly * Decrease Significantly Value) + (Percent Eliminating Farmed Fish * Elimination Value) + (Percent Never Ate Farmed Fish * Never Ate Value)) * Normal Farmed Fish Consumption * Farmed Fish Elasticity * (Average Farmed Fish Lifespan + Days of Suffering from Farmed Fish Slaughter)) + (((Percent Increasing Sea Fish * Increase Value) + (Percent Staying Same with Sea Fish * Staying Same Value) + (Percent Decreasing Sea Fish Slightly * Decrease Slightly Value) + (Percent Decreasing Sea Fish Significantly * Decrease Significantly Value) + (Percent Eliminating Sea Fish * Elimination Value) + (Percent Never Ate Sea Fish * Never Ate Value)) * Normal Sea Fish Consumption * Sea Fish Elasticity * Days of Suffering from Sea Fish Slaughter) * Response Bias * Desirability Bias
[7]: Feel free to check the formula for accuracy and also check to make sure the calculator implements the formula correctly. I worry that the added accuracy from the complex calculator is outweighed by the risk that the formula is wrong.


Edited 18 June to correct two typos and update footnote #2.

Also cross-posted on my blog.