Which effective altruism projects look disingenuous?

You are right that if someone only cares about their favorite charity, then donating through GM doesn't give them any value. After all, GM never helps you to get more value for your favorite charity than you could get by donating directly to your favorite charity. But we also don't claim that we do that. On our website, we say: "Give to both your favorite charity and a super-effective charity recommended by experts. We'll add to your donations." (The EA newsletter text frames things slightly differently and perhaps that's indeed not the optimal way of promoting GM.)

But if someone cares about both their favorite charity and about giving effectively, donating through GM can get them more value. Keep in mind that our target audience are non-EA donors, many of whom haven't heard of EA or about our highly effective charities before.

In our studies we find that many non-EA people (ca. half of our MechanicalTurk participants!) are willing to split their donation 50/50 between their favorite and a highly effective charity when they are offered such a splitting option even if no matching is offered. This shows that surprisingly many people do have a preference to give to effective charities. They just don't know about effective charities yet and don't consider the option to split their donation. The point of GM is to inform non-EA donors about effective charities and offer them this splitting option.

Suppose you have a donor who cares about their favorite charity and a very effective charity. They want to give 90% to their favorite and 10% to the effective charity. They could either donate directly to these two charities or they could donate through GM. If they donate through GM, the system adds on top of their donations. 

The part that is added on top of their favorite charity is clearly counterfactual because the matching funder wouldn't have given to that charity. The part that is added on top of the effective charity is less counterfactual because the matching funder would have given anyway to effective charities. But in expectation it is partly counterfactual because the donor can influence which specific effective charity this part of the funding should go to (and many donors may care much more about some effective charities than others). (Your efficient market hypothesis is interesting and I haven’t considered it. But I doubt that the market for effective charities is completely efficient.)

As Aaron pointed out, all of this is transparently explained on our FAQ page.

Do my matched donations have an impact?

Yes. The donors who provided the matching funding would likely not have donated to the specific charities that you have chosen. Therefore, by making a donation through Giving Multiplier, you don't just decide to which charities your own money goes to but you also decide to which specific charities the added (i.e. matched) amounts—that were provided by the matching funders—go to. Note that most matching funders likely would have donated their amounts to a highly effective charity per default. But they would not have donated to your favorite charity and it's unlikely that they would have donated to exactly the effective charity that you have chosen.

Our website is new and if there are ways to improve, we'd consider these. But to be clear: there is absolutely no intent of deceiving donors. 

Donation multiplier

Yes, it's a similar idea to the "Matching as donor coordination" idea I describe in this post.  (Feel free to contact me if you have any thoughts.)

A new strategy for broadening the appeal of effective giving (

Thanks for these really helpful suggestions, Peter!

We are planning to test some of things you suggest. We kept our post-donation survey short because we wanted to focus on our main research question and not try to do too many things at once. But if we end up having a lot of donors, we might send them a survey via email to find out more about their demographics, beliefs and preferences. We're not planning to do A/B testing at this point. But if we're starting to get lots of donors, we'd definitely consider doing A/B testing to optimize the user experience and get more people to donate.

At this point, our primary goal is to test if the technique works in the real world and if we can get enough donors.  Yes, we want to do media releases to get more traffic. And we are trying to partner with organizations and services to spread the word. I like your idea of reaching out to workplace giving services. If you have concrete ones in mind or have ideas how I could find these, please shoot me a DM!

A new strategy for broadening the appeal of effective giving (

This is a good point and we've considered it. I agree that there are advantages to allowing matchers to support only specific causes (or charities). 

But there are also downsides. In addition to the ones you list below, the matching system would be somewhat less honest. Since the matcher would per default have donated to that cause/charity anyway, you as a donor don't really influence where the matcher's funding goes to. With our current system, in contrast, you do influence to which specific charity/cause the matcher's funding goes to. But this comes at the costs of the matching funder, who has to be willing to support any of the nine effective charities we currently list.

I still think it's worth thinking more about allowing for cause-specific matchings. But we don't plan to implement it anytime soon.

A new strategy for broadening the appeal of effective giving (

It would be great to do that at a later point. Note that you already now can donate from anywhere in the world, but donations are only tax-deductible in the US.