Counterintuitive statistics (i): a fair coin game.

I’ve never been good at playing football 1. I started playing again last year and I have scored more own goals than goals for my team. Also, I support the RCD Espanyol 2, which has spent last season in the second division and has miraculously ascended to the first division last week. And to be honest, I only watch games to spend time with my...

For the last weeks at Wallapop, we have been interviewing candidates for a Data Scientist position. Our current interview process is quite standard, but there are some things we would like to change about the process. We were talking about it during lunch, and I saw my opportunity to propose one of my hot takes: “We should start doing Leetcode...

The other day I was interviewing a developer for a position at Wallapop. The candidate was a little bit junior, but I enjoyed their technical assignment and the conversation was going great. One of the questions I had to ask was

Explore the critical considerations and potential pitfalls of relying solely on A/B testing in making business decisions. While A/B testing is a valuable tool, this post challenges the assumption of exchangeability between past and future data, emphasizing the dynamic nature of the business environment. I propose two solutions (1) validating the...