The Paradox of Invitations

Lately I’ve been intrigued by the idea of website and web app invitations. You join a website and then gain some benefit (as does the site) by inviting a bunch of your friends. A lot of these invitation widgets access your e-mail, Facebook, or LinkedIn accounts. You click “permission to access gmail,” and all of a sudden you’re presented with a list of 300 e-mail address from which to choose.

I don’t know about you, but at that point, unless the incentive for getting a friend to join is really good or if I have someone specific in mind, I just skip the invitations. It’s the paradox of choice: I’m simply overwhelmed by the sheer number of Facebook friends or e-mail addresses from which to choose, and so I choose none.

I’m wondering if there’s a better way for a website to suggest invites to a new user. Thus I propose the following experiment:

Borrow a website that gets thousands of new users every month. Randomly rotate the format of the invitation page so that each of the following invitation formats are equally distributed (thus, when User A lands on the invitation page, he sees Scenario 1, then the next user sees Scenario 2 instead [and does not know of the existence of Scenario 1] and so on):


  1. Regular invitation page where you are given a list of all of your Facebook friends and are asked to pick as many as you’d like.
  2. Invite page where you are given a list of all your Facebook friends and are asked to pick 10 of them.
  3. Invite page where you are given a list of all your Facebook friends and are asked to pick 5 of them.
  4. Invite page where you are given a list of all your Facebook friends and are asked to pick a specific group with no quantifiable guidelines. I.e., your best friends, your immediate family members, your coworkers.

The invitations would read as follows: “Hey! I just signed up for this fascinating new site. I have the one-time option of inviting exactly 10 of my friends and colleagues, and I chose you. Check it out if you have a minute.” (Where the number “10” matches Scenario 2.)

The results I’m interested in are (a) the number of invitations per new site user (not “new site users who decides to invite people”) and (b) the number of conversions (new sign ups) as a result of the invitations.

My hypothesis is that Scenario 4 will result in the most invitations per new user because the assigned context makes it easy for our minds to jump to specific faces and names without much thought. However, I would propose that it will be a much closer contest between scenarios 3 and 4 for the number of invite signups per new user. Scenario 4 is somewhat flattering and will target people who generally trust your taste, but Scenario 3 is flattering in a different way: The quantifiable number in the invitation makes people feel like they’re in a very limited, exclusive, elite group (or maybe they’ll feel like they’re the people to whom you pass on annoying website invites, I don’t know).

I wish I could run this experiment on my blog, but I think it would be more effective if tried on a much heavier trafficked website. Thus I’ve proposed the experiment to behavioral economist Dan Ariely (isn’t it cool that we live in a world where you can propose an idea to a bestselling author and he’ll actually read it? Perhaps even the next day?) [UPDATE: I heard back from Dan, and he’s going to keep an eye out for sites to try this method, but if you know anyone who runs a popular website with whom we could try this little experiment, contact me at]

What’s your hypothesis?

8 thoughts on “The Paradox of Invitations”

  1. I believe this is how hulu and g.mail started – the “elite, invitation by user only” set up. It works, especially at the beginning of a new buzz-worthy site. I’m no behavioral economist, but if you make people feel like they’re sharing a limited commodity (which is what would happen if you can only invite 5 folks to join), then you’re essentially fabricating a sort of supply and demand. However, if it’s the kind of website/app that any old Joe can stumble upon and sign up for, then this “elite invite” scenario doesn’t quite work. Thus, if your website is public, I think that cuing people to “invite your family” or “invite your college a cappella troupe” will make people think of “oh yea, Jim would totally dig this” instead of the massive “here’s all your friends – invite them” scenario that overwhelms and stagnates you. Make sense? In short, I agree with your hypothesis for the most part.

    • Ah, so you’re saying that a limited number of invites would be powerful for a by-invite-only site, but maybe not so much for an anyone-can-join site? I could see that. Although I think there’s something inherently elite that YOU were chosen out of the 100s of Facebook friends that person has (the invite could even say, “I chose you out of my 794 Facebook friends to get this invite”).

      I like the a cappella option. Andy on The Office would be delighted (as would my brother).

  2. Or they should have like a browser or something that can going through your list of Facebook friends and make a list of friends who have or might have the interest of the site depending on their interests. And you, as the new user, can choose people from that list to invite or not. Oh, they can even announce it to the world for you through Tweeter or whatever that you just signed up for this site and invited these friends and somewhat sort tempting it to see what they are missing by clicking that link.

    • You know, I think Facebook is trying to do that–it’s trying to get users to sort their friends into groups. So that might really help the invitation process–instead of choosing friends OR family, you just click the pre-made groups for friends AND family.

      Twitter pretty much just broadcasts the link. You can add @jameystegmaier to bring it to my attention, for example, but that’s the closest you can get.

  3. As a frequent joiner, rare passer and even less frequent ‘all access pass’ distributor (ie I don’t let the website link to my other information) I find your hypothesis very interesting. I can tell you, for example, that when I got a personalized invitation to sniqueaway – the e-mail said that select trip adviser users were being offered membership – I only passed it along to those of my friends for whom I knew there was an interest in last minute travel. I probably have friends who would be interested but I just didn’t know it or didn’t think of them. How could I have a way to increase the likelihood of remembering these friends without feeling like my privacy was being violated by the website?

    • So the exclusive, personalized invitation did it for you too? I don’t know how much of your friends’ data Facebook apps can access, but when you try to invite friends through Sniqueaway, the Facebook Connect app could potentially recognize all of your friends who have marked “travel” as an interest and suggest you invite them.

  4. One other thought: On sites like SniqueAway or BidDeal, if you invite a few friends, you get bonus credits…but only if those friends sign up AND buy something on the site. That makes sense for the site, but adding that level of uncertainty doesn’t really help to persuade a new user to invite friends. I would propose that a more effective method would be to limit the number of invitations and offer the new user the follow:

    $1 in site credits for invites sent (limit 5)
    $5 in site credits for each signup as a result of your invitation
    $20 in site credits (scalable) for each new signup who buys something on the site

  5. I like the idea of combining limited sign ups with big rewards if the new users make purchases – because then it forces you to really think about who you send it to – why waste your 5 on people who won’t join.


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