by Brian Tomasik
First written: 28 Jan. 2012; last edited: 19 Feb. 2016

## Example feedback

Below are selected viewer responses to the video, all from Dec. 2011. For more, see How to Give Encouragement to Several New Vegetarians in Just a Few Minutes.

Here are some sample ads leading to the landing page, from a Vegan Outreach campaign during summer 2012. (Note: The updated ads do not contain veganoutreach.org underneath the title, which should help avoid scaring away those who aren't already sympathetic.)

## Appendix: 100-Yard-Line Model

Summary: Naive estimators of veg conversion are roughly unbiased estimators of your total counterfactual contribution to veg conversion, at least according to one simple model.

In a comment on "The power of effective activism," Roman Duda asked whether veg-conversion calculations like the one in my piece don't

assume that each person [whom vegan leafleter] Joe convinces wouldn't have become vegetarian if it hadn't been for Joe? But surely Joe is not the only force shaping individuals towards becoming vegetarians. So if Joe convinces someone to become vegetarian, he may 'just' be bringing forward in time when that person becomes vegetarian. This is likely to be the case for at least some of the individuals that Joe convinces. So the estimate as it stands is probably overly optimistic.

My reply is as follows. Yes, some of the people we convince were already on the border of being converted anyway, but there might be lots of other people who get pushed further along and don't get all the way to veg*ism by our influence. If we picture the path to veg*ism as a 100-yard line, then maybe we push everyone along by 20 yards. 1/5 of people cross the line, and this is what we see, but the other 4/5 get pushed closer too. (Obviously an overly simplistic model, but it illustrates the idea.)

Here's an elaboration on the 100-yard-line model for veg conversion. Say there are K influences encouraging people toward veg*ism (e.g., The Humane League's veg ads, work by other veg groups, movies like Food, Inc., influence by friends, religious sentiments, etc.). Say there are N total veg conversions due to all these factors combined. Let pi, i = 1,...,K be the sum of distances by which the ith influence pushes people along, aggregated over all people. So for example, if The Humane League's veg ads push people twice as far or push twice as many people as hearing news stories about factory farming does, then pTHL = 2 * pnews stories. Let fi = pi / (Σi pi). If the influences come in a random order (e.g., sometimes veg ads happen before influence by friends and sometimes influence by friends happens first), then the number of observed conversions due to the ith influence will have the expected value fi * N, because, for example, an influence that pushes people twice as far along will result in them crossing the finish line twice as much, and an influence that reaches twice as many people will result in twice as many crosses of the finish line. In other words, in apportioning responsibility for veg conversions, the actual number of people that you cause to cross the finish line is an unbiased estimator of your group's causal contribution to all N veg conversions.

Once again, the intuition is that, yes, some of the people you convert with veg ads would have gone veg due to other reasons. But some of the people you don't convert will now go veg due to something else because you helped them along the road.

Unfortunately, this reasoning isn't quite right, as xodarap explains. However, the general idea seems roughly correct to at least within a reasonable multiplicative factor.