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Pinterest Engineering: Meet Qiaochu Li

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Written by Life at Pinterest Team

Our engineers are building an inspired and inclusive platform for Pinterest users worldwide. In the Pinterest Engineering series, you’ll meet the people behind the product, learn about their work and why they chose to grow their career with the Pinterest team. Meet Qiaochu Li, Manager II, Data Science! 

Hi Qiaochu! Thanks for joining us today. Can you start by sharing more about your current role at Pinterest? 

I joined Pinterest as a Data Scientist and then transitioned into a Data Science Manager. I’m currently leading a team of talented data scientists working on emerging challenges in ads measurement and conversion visibility. Our core mission is to provide data and insights on how ads at Pinterest are creating business value for our advertising partners, so that we can build trust with advertisers and help them establish a successful business on Pinterest.

This is a complex realm with its unique challenges. For instance, we continuously face questions like: How can we build better foundational data for our AI-powered ads system? How can we help advertisers accurately measure ROI (Return on Investment) of their ads on Pinterest? How can we uncover insights on how ads help Pinners buy the products they love, while respecting each individual Pinner’s privacy? Many of these open questions require a deep understanding of our data and rigorous research using scientific methods such as statistical modeling and causal inference - all of which are key jobs for us as a data science team.

You’ve been at Pinterest since 2020, what made you want to grow your career here? 

I would say the main reason is the incredible opportunity for fast learning and continuous growth. Over the past few years, I have experienced the sharpest ascent in both skills and mindset in my career, and I couldn’t be more excited about what lies ahead. I largely attribute my growth to the exposure I’ve had to a wide range of challenging and impactful problems. In just my first year, I had the opportunity to work with four product and engineering teams, which provided me a comprehensive understanding of our ads system from end to end. The highlight of my first year was when my research results influenced executive-level decisions –an achievement I never imagined when joining Pinterest several months ago. Experiences like this have been instrumental in not only expanding my domain knowledge in digital advertising but also equipping me with invaluable insights into how to drive business impact with the power of data.

Another driving force for my growth is Pinterest’s strong culture for creating belonging and nurturing personal growth. Throughout my time here, I have been fortunate to receive mentorship from my manager and other senior leaders from various teams who have dedicated their time and offered advice, contributing to my professional development. Their support has been the compass guiding me through the most challenging crossroads of my career. This caring and empowering culture has inspired me to carry the torch forward. Beyond supporting the growth for my team members, I’m actively participating in our “Data Mentorship” program as a volunteer mentor and have helped several colleagues across the company develop their data skills. It brings me great fulfillment to witness all of us growing together and achieving success in our respective fields.

What’s one project or achievement that you’re most proud of? 

There are many highlights along the journey, but one particular project stands out in my mind – Split Testing. This innovative measurement product allows advertisers to run A/B tests on their campaigns so that they can understand and scale what performs best. When I started this venture, it was unclear whether this type of work was possible given a variety of unknown technical challenges. However, as a data scientist, I’m always thrilled by these “unknowns” and firmly believe the answers can only be found in solid data. I took the challenge as the first one to plunge into this problem: I conducted a series of simulation analyses to establish the theoretical conditions for reliable testing, and developed prototype statistical algorithms that laid the technical foundation for the product. These promising insights garnered the support of Product and Engineering partners to test our idea within a group of advertisers. After several months’ hard work setting up the experiment and analyzing the real-world data, I was finally able to prove with concrete evidence that a practical Split Testing product was not only valuable for our advertisers but very much feasible.

The fruits of this year-long endeavor eventually led to the decision to build out a Split Testing product, which has gained remarkable momentum. This past September, at Pinterest’s Investor Day, Split Testing was highlighted as an example of our ads product innovation! I’m so proud of this milestone as it serves as a powerful testament to how data is at the heart of driving product innovation at Pinterest.

What’s one piece of advice you’d have for someone that is interested in a career at Pinterest? 

Be curious and embrace possibilities. Don’t let your past define your future. Taking myself as an example, I was originally trained as a physical scientist but now have found my calling in digital ads. While the two fields may appear unrelated, I discovered that my training in quantitative research and experience in experimentation became my unique asset for solving complex technical and product problems in advertising. You too may find your unforeseen opportunities in an unexpected area. One aspect that truly resonates with me about Pinterest is its commitment to fostering a diverse and inclusive community. Regardless of your background, you will be encouraged to push your boundaries and leverage your strength to chart your own path towards success. 

What are you currently Pinning? 

I’m a huge fan of photography. My boards are filled with a rich collection of camera gears and stunning landscape photography ideas. Lately, I became really into gardening and can’t stop pinning all those amazing garden design ideas, which I hope will soon turn into a massive DIY project in my backyard!

Grow your career at Pinterest by applying to an open role today. For more articles by our Engineering team, check out the Pinterest Engineering Blog

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