Written by Guido Jansen in
August 2010


When we receive a gift, we feel a need to reciprocate.


Give things away for free. A free account, a free report, a free workshop, a gift card etc. Preferably something that people won't expect to get for free. People will feel the need to do something in return, whether it's buying something at your shop directly or referring friends (which you can make easy with social media integration). Note: if your competitors are also giving things away for free then people might also expect this from you and it's no longer a real gift.

Recent posts
Optimization hierarchy of evidence
Optimization hierarchy of evidence

A hierarchy of evidence (or levels of evidence) is a heuristic used to rank the relative strength of results obtained from scientific research. I've created a version of this chart/pyramid applied to CRO which you can see below. It contains the options we have as optimizers and tools and methods we often use to gather data.

Datascience can do what?
Datascience can do what?

This is a bonus episode with Emily Robinson (Senior Data Scientist at Warby Parker) en Lukas Vermeer (Director of Experimentation at In her earlier session that day, Emily said that real progress starts when you put your work online for others to see and comment on which in this case was about Github. Someone from the audience wondered how that works out in larger companies where a manager or even a legal department might not be overly joyous about that to say the least so I asked Emily about her thoughts on that. Recorded live with audience pre-covid-19 at the Conversion Hotel conference in november 2019 on the island of Texel in The Netherlands. (oorspronkelijk gepubliceerd op