I have spent the past few months working as a PhD intern at Twitter’s Cortex research organisation on projects relating to fairness, transparency and decision making under uncertainty. I have enjoyed working closely with engineers, researchers and external academic collaborators from a number of backgrounds: in our team alone there are PhDs in political science, economics, statistics and computer science. The team collaborates across much of Twitter and I have been working with the Health, META (ML Ethics, Transparency and Accountability) and Cortex Applied Research organisations to impart Bayesian methodology and increased transparency to platforms supporting many of the algorithmic approaches employed by Twitter, as well as carrying out some interrogative analyses on these methods as Twitter pushes to improve on matters of fairness and bias. My work impacts models spanning a number of purposes, from recommending users to each other, to detecting hate speech and threats to healthy conversation on Twitter. It has been a fulfilling experience to work as part of a senior team, working on impactful projects, learning new technologies, presenting at internal reading groups and more. My ideas for my own projects as well as at a greater scale for the organisation and team as a whole are heard, and my past experiences from my PhD so far have given me plenty of insights and value to offer in this environment. The scale of data (often in the trillions of rows) is still quite mind blowing, and the unique challenges associated alongside the modes of working at Twitter will definitely be something that stays with me as I resume my PhD, alongside valuable collaborations that will hopefully last into the future.