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Preply case study: When social proof kills conversion?

Overview is a leading marketplace that helps students find private tutors to study online. This service charges a commision for every of tutors’ hours.


We identified that a significant proportion of users dropped off on the homepage, where they are asked to choose a subject they want to find tutor in and a city where this tutor must be located.

After completing these two field users are presented with a list of tutors based on their search criteria.

Our goal was to increase revenue from new visitors by optimizing CTR from landing page to search results.

Key Performance Indicator (KPI): revenue per new visitor

Traffic sources: social, display, direct, organic and paid search

Device targeting: desktop

Traffic allocation: A / B (50% / 50%)


The area above the desktop fold:


With the mission at hand our top priority was to optimize user experience during the first few seconds user lands on site.

You are probably aware of the fact that the average attention span of homo sapiens on the website is shrinking every year (from 12 seconds in 2008 to 8.2 seconds in 2015).

So the importance of optimizing user experience in the first seconds of interacting with site could not be exaggerated.

Social proof

Here are the elements are used as social proof and define user experience above the fold.



The total number of customers:


Normally, social proof is considered to increase conversion rate. However, we hypothesized that the effect would be the opposite in this case because we ask for a low commitment conversion on the homepage.

That is, we don’t need to use the hard sell, just ask to select a subject for study and city. So social proof elements are not needed and could serve as a distraction from the main CTA.

Moreover, the average fold level included a preview of the second screen below the fold.

This motivated users to scroll to the second screen below the fold distracting users from searching for a tutor.

These tactics work well when selling complex SaaS products because we need a user to read more than just one screen. However, it’s unnecessary when asking for a low-commitment conversion.

To validate this hypothesis we created a regression model and found that scrolling and clicking on elements below the fold negatively correlated with conversion rate.

Hero image

The hero image is quite relevant to the value proposition but provides no additional value in explaining benefits of service.


Moreover, click maps showed that the hero image grabbed significant amount of user attention, depriving our key conversion of attention. This is a critically important issue when optimizing user experience of the first seconds after landing on site. So this attention is “stolen” from the main CTA and the picture serves as a distraction.

There was another visual element on homepage that drew attention – a horizontal block with filters of most popular cities and CTA to choose Skype*:


*Users who chose to find tutors Skype had higher LTV and the operational costs to convert them are lower than in the case of choosing cities. But changing the UI of this CTA was the hypothesis of next experiment and was tested separately.


The decision was to make radical redesign that will eliminate all above mentioned hypothetical problems:

  • Move trust badges and “Only 3 steps to finding a tutor” progress message below the fold of the page.
  • Delete hero image.
  • Place block with cities and Skype CTA on the edge of the fold.

The hypothesis was that a clearer UI with main CTA in the first line of the visual hierarchy will increase CTR to search.

Control page



Alternative page

marketplace landing page


In total, 133,252 visitors took part in the study. The duration of the experiment was 24 days and it reached 95% statistical significance level for main KPIs.

Progression to next stage of the funnel (CTR from home page to search results) increased by 17,23%. That resulted in 11,2% growth of revenue per new user.

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