It's taken me a while, but I've considered all the info you've provided and have a possible answer for you. First I want to summarise my understanding of what you've done, just to make sure we're on the same page.
In summary, you measured the rate of user registrations on both your wish list and order confirmation pages for a period of some weeks. You've then broken up those results into three main groups:
- Prior to the test;
- During the test; and,
- Following the test.
You found that the rate of registrations for the periods prior to and following the test period was almost on average double that during the test period. The only difference, as far as you can see, is that during the test period you provided the option for users to use either their Facebook or Google credentials to login.
Now, I know I asked you a lot of questions in my comments, but what I was trying to do was get a feel for the respective user interfaces and workflows between the 'wish list' and 'order confirmation' pages. I wanted to understand why there may have been a difference specifically between these two, rather than an overall difference between the level of registrations with and without the social media login options.
Unfortunately, without screenshots of the actual user interfaces or the ability to go and visit the site in question and 'try it out' myself, I have an answer that will hopefully shed some light on your problem, but may not answer it entirely. Hopefully it helps with your presentation!
So-called 'social media login buttons' have now been around for five or so years. It wasn't long before these options took off and became evermore prevalent in websites from all sorts of fields. This seemed to coincide with a marked improvement in login rates and a reduction in failed login attempts.
Some of the drivers towards using social login buttons were:
However, while the above may have all been true (and, to some extent still is), something changed in June 2013. Namely, the revelation of classified NSA documents by Edward Snowden opened the eyes of a lot of people in terms of their privacy. This was only the beginning, as a number of events have since occured that have raised the ire of internet users (e.g. revenge porn sites, the so-called 'fappening', the highly targeted nature of online advertising, suspicious terms & conditions associated with the use of certain websites/apps, etc etc). This has all culminated to the embracing by some of the largest IT companies to protect the privacy of its users (e.g. Apple's allowance of ad blockers since iOS 9, Apple's current fight with the FBI, etc).
As a result, what we have today is a somewhat more sceptical and aware audience from which to attract our user base. And increasingly we're seeing 'security experts' and a range of 'bloggers' arguing against the use of social media login buttons with arguments like:
- You are weakening the security of your Facebook, Google, etc accounts by reusing these across many multiple sites.
- You are weakening the security of the site you are logging into with your Facebook, Google, etc credentials.
- You are tying another identity to what may be unrelated or conflicting activities.
- You are adding to the pool of 'public' information about you.
However, the most relevant factor to your scenario is that more and more people are recommending that users "avoid using social media sign ons for ecommerce sites". While this type of advice may not yet be resonating with a majority of users, it is becoming more prevalent.
I suspect that in your instance, when a user got to the stage of an actual order 'confirmation', they were hesitating about whether it was 'safe' to use their social media credentias to log in, especially since we're likely to be talking about new users (on the basis that your test was only run for a short period and that existing users are more likely to already be registered).
However, for whatever reason, your 'wish list' workflow/interface didn't trigger the same hesitancy. This could in fact be due to the fact there is a clear vertical divider on what is a newly routed page. Therefore, what you saw as a "pretty bad" interface was actually something that is working in your favour, especially if the higher registrations were not due to social media clicks.
In a nutshell, people have woken up to what really goes in with the big Facebook and Google enterprises in terms of datamining their personal details and web history and targeting them with 'personalised' advertising etc and more and more people are growing uncomfortable with this and are choosing to avoid using their social media sign ons for ecommerce sites.
You may be interested in the following article:
I hope all this helps you pull something together for your presentation next week.