Chattermill Analytics Limited - Senior Machine Learning Scientist
Requirements
• A deep working knowledge of transformer architectures. • Strong PyTorch skills, with the ability to write custom training loops, modify model architectures, and debug issues at the tensor level. Ideally, experience with parameter-efficient fine-tuning techniques such as LoRA • Extensive experience working with large-scale, messy real-world text data, including classification, extraction, embeddings, re-rankers, clustering, and search. • Experience in instruction fine-tuning and serving language models, familiarity with frameworks such as vLLM, DeepSpeed, or similar tools • A solid grounding in classical ML and statistics, and the judgement to choose simpler methods when they’re the right solution. • Practical experience building with GenAI and agentic patterns. • Excellent communication skills and confidence translating complex technical concepts for non-technical audiences (and vice versa!). • Technical curiosity and a keen interest in AI – a love of experimenting to make the most of available technology. • High ownership and initiative, with the ability to identify problems, prioritise effectively, and drive solutions forward. • ➕It would be a bonus if you: • MSc/PhD in Computer Science, Machine Learning, Artificial Intelligence, Data Science, Computational Linguistics or a closely related STEM field. • Experience with reinforcement learning techniques, such as with verifiable reward (RLVR) • 🔎 Our Hiring Process • 1. Let’s introduce ourselves – you’ll complete an introductory asynchronous interview - we’d love to learn more about you, your ambitions, and what you’re looking for in your next step. • 2. Get to know your would-be manager – you’ll have a call with Aji, our Chief Scientist, to learn more about the role and show off your experience. • 3. Show us how you work – you'll complete a short take home assignment • 4. Get to know your would-be team – You'll meet a mix of people who you'll be working closely with from the Data Science, Engineering and Product teams. • 5. How our values and your career goals align – you’ll have a call with our cofounder to learn more about life at Chattermill and ensure we’re the right place for your next stage of growth. • We are obsessed with experience – We take our mission to rid the world of bad Customer Experience seriously, and we practice what we preach. • We believe in the power of trust – Whether it's with each other, our customers, partners, or other stakeholders, we always communicate with openness and trust.
Responsibilities
• Unlike many companies, we use our own custom models, specialised for customer feedback, across various parts of the stack: extraction, retrieval, reranking, summarisation, and sentiment analysis. We are also pragmatic and understand that the right solution can be a combination of off-the-shelf LLMs, bespoke fine-tuned models, and sometimes techniques that utilise no LLM at all. • Train, evaluate, and iterate on ML models and agentic systems for customer feedback, including owning our custom fine-tuning pipelines. Run experiments end-to-end, track results rigorously, and make clear recommendations on what to ship, iterate, or retire. • Build and maintain LLM-powered features: retrieval pipelines, reranking systems, insight agents, data mining agents, and automated taxonomy generation. • Design and run robust evaluation frameworks: build test sets, define metrics, evaluate non-deterministic systems, handle class imbalance, and automate checkpoint comparisons. • Improve and extend semantic search and retrieval, evolving from embedding-based approaches toward more advanced methods. • Write production-quality code and collaborate closely with Engineering on productionisation, model serving, data pipelines, and monitoring. • Work with Product and Commercial teams to translate business needs into practical ML solutions, and support client evaluations and accuracy benchmarking. • Mentor team members, review code and research, and bring relevant advances from the literature into the product.
Benefits
• ❤️ Monthly Health & Wellness budget, increasing with length of service • 📚 Annual Learning and Development budget, increasing with length of service • 🤸🏽♂️ Flexible working in a choice-first environment - we trust the way you want to work! • 🖥️ Work From Home Allowance • 🌴 25 Holiday Days + your local bank holidays, plus an extra day for every year of service • 🎂 Your birthday off • 🍼 Enhanced Family Leave (UK Only), Fertility Leave, and Neonatal Leave • ⚕️ Optional Healthcare Plan • 🛟 Life & income protection (Location dependent) • 🤝 Employee Assistance Programme (UK Only)
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